ON THE MORPHOLOGY OF THE HELIClNIDJi. 759 
patches by digging holes to lay their eggs ; so they asked the 
Shark to take the Megapodes away. This was done, but now the 
natives missed the Megapodes" eggs, so they asked the Shark to 
bring the Megapodes back but to confine them to one spot. 
This request was also complied with, and the result may now be 
seen. The Megapodes lay their eggs in two large and broad 
sandy spaces, and nowhere else on the island. 
I suspect that there is more than a grain of true history in 
this legend, and that it records the fact that when the ancestors 
of the natives came to the island, they brought with them two 
raaiii staples of their food-supply — yams and Megapodes. 
35. Contributions to the Morphology ut* the Group Neritacea 
of the xVspidohranch Gastropods. — Part II. The Heli- 
ciNiD.^. By Gilbert C. Bourne, M.A., D.Sc, F.R.S., 
F.Z.S. 
[Received April 29, 1911 : Read May 9, 1911.] 
(Plates XXX.-XLII.*) 
When, two years ago, the Society published the first part of my 
contributions to the morphology of the Neritacea (2), I had already 
accumulated a number of observations on the anatomy of the 
Helicinida?, but deferred the publication of them until I was able 
to obtain specimens of difteient species from various parts of 
the Pacific region. Having experienced considei'able difficulty in 
obtaining specimens sufiiciently well preserved for microscopical 
examination, the publication of my results has been long delayed, 
with the result that I lose the cltiim to priority for several minor 
discoveries concerning the anatomical features of this family, for, 
in the meantime, Thiele (10) has given an account of the anatomy 
of Hyclrocena cattaroensis in which is included a description of 
the female generative organs oi Helichia kuharyi, and the following 
descriptions lose much of the novelty they Avould have possessed 
had they been published as soon as the facts were ascertained. 
Previous to the publication of Thiele's paper, our knowledge of 
the anatomy of the Helicinidne rested, for the most part, on 
Isenkrahe's (4) account of the anatomy of Helicina titanica. 
Isenkrahe gave a sufficiently accurate description of the external 
anatomy, the muscular system, the greater part of the alimentary 
tract, and the pulmonary cavity, but he failed altogether to 
distinguish the kidney, and his descriptions of the heart, the 
nervous system, and the reproiluctive organs are defective. These 
imperfections notwithstanding, Isenkrahe was able to confiiiu 
Troschel's opinion that Helicina, on account of its rhipidoglossate 
dentition and other anatomical characters, was closely related to 
the Neritidaj. 
Von Jhering (5) in 1877 placed the Helicinacea and Proserpinacea 
* For explanation of the Plates see pp. 806-809. 
760 PROF. G. C. BOURXE OX THE 
in his class Orthoneura, order Rostrifera, sub-order Rhipidoglossa, 
and gave a fairly accurate description, unaccompanied by a figure, 
of the nervous system of Helicina [Sturanya Wagner) beryllina 
Gld. E. L. Bouvier (3), in his gi'eat work on the nervous system 
of Prosobranch Gastropods, gave a ver}^ complete account of the 
nervous system of H. sagraiana d'Orb. and H. hrchsiliensis Gray, 
laying stress on its close resemblance to the nervous system of the 
Neritidje, and in addition he made some further observations on 
the general anatomy, partly confirming and paitly correcting and 
adding to Isenki-ahe's descriptions. In 1902 Thiele (9) described 
the male generative organs of Helicina jajwnica, and last year 
he gave a description with a diagram of the female organs of 
a. kubaryi, in addition to a succinct but sufiiciently exhaustive 
account of the general anatomy of Hydrocena cattaroensis . 
The geographical distribution of the Helicinidje, as is well 
known, presents several interesting and diflicult problems. By 
far the greater number of species are insular and confined to the 
tropics. Such species as are foiuid on continents are for the 
most part limited to regions near the coast, very few being known 
to occur any considerable distance inland, i^o Helicinidse are 
recorded from Africa. In Europe the gioup is i-epresented only 
by the genus Hydrocena from the Dalmatian coast, and this genus, 
as Thiele's recent work has sho\^Ti, diftei-s in several important 
anatomical characters from Helicina and its more closely allied 
genera. Georissa, a subgenus of Proserpina, is the only represen- 
tative of the gi'oup in India, and no Helicinidje have as yet been 
recorded from Ceylon, The number of genera and species reaches 
its maximum in the Antilles. The genus Helicina, as restricted 
by Wagner, is fairly abundant in Mexico and the Central 
American republics, and extends northwards into Texas and 
Florida, southwards into Ecuador and Peru on the west coast and 
to the south of Brazil on the east coast of S. America. Few 
species, however, are recorded from the Pacific coast of S.America, 
but, notwithstanding their comparative rarity on these shores, 
the group reappears in great abundance in the Pacific islands, 
extending as far east as the Marquesas and Paumotu Islands, and 
having many representatives in the Society, Samoan, Friendly 
and Fiji Islands, and in the JSTew Hebrides and New Caledonia. 
Several species occur on the east coast of Australia, and some 
few are recorded from New Guinea, Celebes, Borneo, and Sumatra ; 
none, so far as I can ascertain , from Java. But in this part of 
the world the Helicinidae attain their maximum in the Philippine 
Islands, which are only second to the Antilles in the number of 
species. From thence the group extends north, beyond the 
tropical zone, to the Bonin Islands and Japan. A few species 
are found beyond the south-east coast of China and Siam, others 
again in the Malay Peninsula and Bm-ma. Several species are 
found in the Andaman and Xicobar Islands, but the group is 
very poorly represented in the Indian Ocean. Aphanocojiia 
(Helicina) theohakliana G. & H. Xevill is recorded from the 
MORPHOLOGY OF THE HELICINIDJ!. 761 
Seychelles, and Pseudotrochatella undulata Morelet is a subfossil 
form from Mauritius. Xone is known from Madagascar. 
In a recent work of great value to the student of geographical 
distribution A. J. Wagner (12) has revised the family Helicinidae, 
and, founding his diagnoses chiefly on the characters of the 
operculum, has broken up the old genus Uelicina into no less 
than thirteen genera, reserving Lamarck's appellation for the 
American and Antillean forms which conform to the oiiginal 
definition of the geniis. Of the remainder I mention the largest 
genera. Sidfurina has its centre in the Philippines and extends 
thence to the Andamans, Nicobars, IMoluccas, New Guinea, and 
Tahiti. Ajj/tanoconia, which also seems to be centred in the 
Philippines, extends wideh', to Japan. S. China, the Malay 
Archipelago, the Andamans, Nicobais, Seychelles, Moluccas, and 
through Micronesia and Melanesia to the Paumotu and Sandwich 
Islands. Shiranya has its centre in Fiji and Tonga, and extends 
thence to the Carolines, Sandwich, Society, Hervey, and Solomon 
Islands. Orohojihana is found in Queensland and N.S. Wales and 
extends through nearly the whole of Polynesia. Pcdceohelicina, 
with its subgenus Ceratopoma, is again a Philippine genus, and 
extends to New Guinea, the Bismarck Archipelago, the Solomon, 
Louisiade and Pelew Islands. The last-named genus is, according 
to Wagner, closely allied to Uelicina sensu restricto. Again, the 
subgenus Retorquata of Uelicina, which occurs in Mexico and 
Centi'al America with outliers in Florida, and Texas, aftbrds, 
according to the same author, a transition to such a characteristic 
Antillean genus as Alcadia. A consideration of these statements 
leads to the conclusion that the Helicinida? are capable, by what 
means we know not, of wide dispersal across seas and oceans, and 
find conditions most suitable to their existence in proximitv to 
the sea. They appear to have originated in RLexico and Central 
America, and to have spread eastwards to the Antilles, whei'e 
they found the conditions specially suitable, and have been 
differentiated into several genera (Alcadia, Lucidella, Entrochatella, 
PriotrochateUa, Froserpina) and numerous species, and one species 
[H. substriata convexa Pf.) has found its May to the Bermudas. 
Others have extended down the eastern coast of S. America, but 
the Atlantic Ocean has proved an impassable barrier to their 
further extension eastward. On the Pacific side the grou}) has 
been transported by some means unknown to us to the Pacific 
Islands, and it would appear from the evidence that it did not at 
first effect a lodgment in the moi-e eastern islands, but in the 
Pliilippines, from which centre it has spread in all directions — 
eastward throughout Polynesia and to the Sandwich Islands, 
southward to New Guinea and Australia, northward to Japan 
and China, westward through the Dutch Indies and Malaya to 
the Andaman and Nicobar Islands. Very few have ti^versed 
the Indian Ocean to reach the Seychelles and Mauritius. 
Very little is known of the geological history of the group. 
Uelicina occurs in the post-Pliocene of N. America, but the 
762 PROF. O. C. BOURNE ON THE 
ancestral forms must have lived at a much earlier period, for 
Proserpina is recorded from the Eocene of the Isle of Wight, and, 
according to Kobelt (6), shells i-eferable to the same genus have 
been found along with Helix, Planorbis, Valvata, and three 
species of Keritina in the Lias of Somerset. There is some reason 
for suspecting the correctness of the identifications in the last 
case, and I am unable to find any cori^oborative evidence of the 
occui'rence of Proser2)ina in the Eocene, but the distribution of 
the Hydrocenida? points to a geological hi.story reaching well 
back into Tertiaiy times. Dawsoniella fi'om the Carboniferous of 
Illinois has been attributed to the Helicinidfe, but I have already, 
in the first section of this memoir, discussed the aflinities of this 
genus and pointed out that it must be a case of convergence. 
However this may be, palaeontology throws very little light on 
the origin and disti'ibution of existing Helicinidfe, and when I 
began this work I hoped, not only to give a full description of the 
anatomy of a typical member of the family, but also, by the 
comparison of the anatomy of Pacific and West Indian forms, to 
discover some clue to the distribution of the group with its two 
main centres in the Antilles and the Philippines. In this, as will 
appear, I have been disappointed. From whatever part of the 
woild they may come, the anatomy of the different species and 
even genera of Helicinidse is so closely similar that it is hard to 
find any difierence between them. It is true that I have not been 
able to procure many species of Pacific Helicinida?, but I have 
examined fairly well preserved specimens of OrobopJiana, Aphano- 
conia, and Pcdceohelicina, and these three genera may be taken as 
typical of the more widely distributed Pacific forms. 
The material at my disposal w^as as follows : — 
I. Antillean forms. 
Alcadia palliata Ads. Contrivence, Waldei'ston, Jamaica. 
Alcadia hoUandi Ads. Swing Hill, Walderston, Jamaica. 
Lucidella aureola Fer. Bog Walk, Spanish Town, Jamaica. 
Eittrochatella ptdchella Gray. Bog Walk, Spanish Town, 
Jamaica. 
The above were kindly collected for me and preserved in 
Perenyi's fluid by Mrs. G. B. LongstaflP, F.L.S. 
II. Pacific, Australian, and Indian forms. 
Aphanoconia goiddiana Forbes, from Torres Straits : for 
specimens of this species I am again indebted to Mrs. 
LongstaflT, who procured them for me from Mr. 0. Hedley, 
of the N.S. Wales Museum. 
Aphanoconia andamanica Benson. 
Aphanoconia merguiensis Pfeiflfer. 
Aphanoconia rogersii, sp. n. 
These three species are from the British Museum and formed 
part of the collection made in the Andaman Islands by Mr. G. Rogei-s. 
MORPHOLOGY OF THE HELICINID.E. 763 
They were numbered respectively 16, 30, and 31. The first two I 
have identified without diflSculty, the third appears to be new 
to science, and I will give a diagnosis of it in the latter part of 
this paper. I am indebted to Mi'. E. A. Smith for these and for 
the two following species : — 
Orohophana pachystoma ponsonhyi Smith. Admiralty Islands. 
Palceohelicina ida' Wagn. Amboina. 
In describing the anatomy it will be convenient to take Alcadia 
as the type, and to note such diffei'ences as may exist between it 
and the other genera at the end of the description of each system 
of oi'gans. 
External Characters, Mantle, Mantle-cavity, 
and Muscular System. 
Isenki'ahe (4) has given an account of these so sufiicient and 
accurate that it is not necessary for me to do more than call 
attention to some special features exhibited in fig. 1 (PI. XXX.), 
which is a I'epresentation of a left side view of Alcadia palliata : 
the mantle has been cut through on the left side close above the 
columellar muscle, the cut has been extended back to nearly the 
extreme hinder end of the mantle-cavity, and the mantle has been 
turned over towards the right. As compared with the Xeritidse, 
in this and in all the other species of Helicinidas that I havo 
examined the foot is attached to the head and body by a longer 
and narroweivpedicle, the opercular lobe is relatively smaller, the 
snout is narrower and longer, the columellar muscles of greater 
antero-posterior length, and the whole body is longer, giving the 
appearance of an increase in the coiling of the visceral mass, but 
this last feature is more apparent than real, as I shall show. 
A glance at the figure shows that the increased length of the 
body is chiefly due to the elongation of the post-tentacular region 
and the part of the body immediately following. Using 
Amaudrut's (1) phrases, we have an almost extreme case of 
" allongement posttentacvilaire," followed by an " allongement 
dorsal," and many of the peculiar features of helicinid anatomy 
areto be explained by the excessive growth in length of these two 
regions. The post-tentacular region lies above the anterior two- 
thirds of the columellar muscle, and its posterior limit is max'ked 
by two or three deep wrinkles of the body-wall. The body-wall 
of this post-tentacular region is fairly stout and muscular, and 
the epidermis is, as a rule, deeply pigmented. The colour differs 
in different species. It is nearly black in Alcadia, grey shading 
posteriorly into white in Eutrochatella pulchella, yellowish gi'ey 
in Lucidella aureola, a dark chocolate-brown in Pala^ohelicina idee, 
and a bright chestnut-brown in Aphanoconia gouldiana. In the 
post-tentacular region are contained the buccal bulb and the 
greater part of the oesophageal pouches. In the dorsal region 
following on the post-tentacular the body-wall is thin and nearly 
764 PEOF. G. C. BOURNE ON THE 
transparent, the musculature is feeble, and the epidermis is not 
pigmented. This dorsal region is relatively of considerable length ; 
its concave lower border corresponds very closely in length with 
the surface of insertion of the left columellar muscle ; its upper 
surface extends back to the pericai-dium. It contains nearly all 
the coils of the intestine, the esophagus, the radular sac, and the 
hinder lobes of the cesophageal pouches. Its roof forms the floor 
of the hinder part of the mantle-cavity. In consequence of the 
elongation of these two regions, but particularly of the dorsal 
region, the mantle-cavity is continued very far back ; so far that, 
measured from its most anterior to its most posterior limit, it 
makes nearly a complete turn of a spiral, whereas in N'erita and 
Neritina it makes little more than half a turn. Broad in front 
where its roof passes from the right to the left columellar muscle, 
the mantle-cavity becomes narrower- and narrower posteriorly and 
ends in a pointed cul-de-sac below and somewhat to the right of the 
lower surface of the visceral mass. Its extreme posterior limit is 
not quite visible in fig. 1 . With the hinder end of the mantle- 
cavity the pericardium has also been cari-ied very far back. It is 
laid open in fig. 1 to show the position of the heart. It will be 
seen that the single auricle seems to lie behind the ventricle, and 
not in front of it as does the larger left auricle in the Neritidse. In 
horizontal sections, such as those depicted on PI. XXXIII. figs. 18 
and 19, this posterior position of the auricle forces itself so much 
upon one's attention that I was led to form the theory that the 
single auricle of the Helicinidte corresponds not to the left and 
laro-er, but to the right and rudimentary auricle of the ISTeritidse ; 
and in my memoir on the morphology of the latter family (2, 
p. 833) I prematurely gave expression to this view, which seemed 
to me the more pi^obable because I found that in correlation with 
an increase of the pallia! vessels in Septaria the right auricle 
became relatively larger and took an obviously larger share in 
carrying blood from the pallial vessels to the ventricle. But since 
then, after a careful study of the relative positions of the kidney, 
the uropore, the rectum, and the heart in the Helicinidse, I have 
satisfied myself that this view was erroneous. 
As a consequence of the dorsal elongation of the body all 
these organs have been rotated through an angle of rather more 
than 90°, in such wise that the pyloric end of the stomach, which 
in the Neritida; is directed forward and to the left, comes to lie 
at the right posterior end of the body in the Helicinida?, and 
the swollen oesophageal end of the stomach, which is posterior 
and somewhat to the left in the Neritidae, is directed anteriorly 
and to the right in the Helicinidae, forming a conspicuous 
rounded prominence at the extreme end of the visceral mass 
(PI. XXX. fig. 1, St:). To understand the nature of this rotatory 
movement the reader should refer to fig. 42 of my memoir on 
the ISTei-itidge. This figure represents a horizontal section of 
Paranerita gagates, and shows the position of the oesophageal (St.) 
and pyloric {St.') divisions of the stomach. It should be noticed 
MORPHOLOGY OF THE HELICINID^. 765 
that the extremity of the visceral mass, lying to the right, is 
wholly occupied by the liver and gonads. If, now, the reader will 
lay a tobacco-pipe in front of him on the table, the bowl (repre- 
senting the oesophageal division of the stomach) to his right, the 
stem (I'epresenting the pyloric division of the stomach) to his left 
front, it will occupy much the same position as does the stomach 
in the figure referred to. If, while the bowl is kept pi-essed 
against the same spot on the table, the stem is lifted up and 
rotated through an angle of rather moi-e than 90° till it points 
over the observer's right shoulder, the whole pipe will have been 
rotated through an angle which brings it into the j^osition of the 
stomach of the Helicinidse — the animal being supposed to be 
placed foot downwards upon the table with its head turned away 
from the observer. As all the organs of the left side of the 
body, including the posterior end of the mantle-cavity, the peri- 
cardium, the heart, the kidney, and the coils of the intestine, 
have shared in this movement of the pyloric end of the stomach, 
their positions have been nearly completely reversed, and the 
left auricle instead of lying in front of the ventricle has come 
to lie behind. The right auricle has entirely disappeared in the 
Helicinidse, and the rectum, having undergone some degree of 
displacement in connection with the above-described movement 
of rotation, is no longer enveloped by the ventricle. 
The kidney has also undergone a curious and at first sight a 
puzzling change of position. In the Neritidte, as described in 
my previous memoir (2, see PI. XLVI. fig. 1 for its position in 
Septaria, PI. LIV. fig. 29 for its position in Paranerita gagates), 
its glandular part lies to the left hand of and partly below the 
rectum : posteriorly the glandular part opens into the sj)acious 
non-glandular bladder or ureter, and the latter runs forward, 
below the glandular part, to open by the uropore into the mantle- 
cavity on the right of and close to the base of the ctenidium. 
In this family the greater part of the kidney lies in the roof 
of the mantle ; it is only its posterior extremity that passes below 
the rectum and invades the visceral mass, where it lies just above 
the pyloric end of the stomach. The effect of the rotation of the 
last-named organ in the Helicinidse is that the kidney has been 
carried i-ound till it comes to lie wholly in the visceral mass, on the 
lower side of the latter, between the loop of the rectum which 
passes round this region and the pyloric division of the stomach, 
as may be seen in the series of sections (PI. XXXIII. figs. 1 7 to 20) 
and in the diagram (PI. XXXIY. fig. 24), which is a reconstruction 
from this series of sections. The kidney, in short, has been 
turned completely round, so that its originally posterior end looks 
to the left front and the uropore opens into the right hinder 
corner of the mantle-cavity, the reno-pericardial canal, main- 
taining its relation to the uropore, into the right posterior corner 
of the pericardium. It is further to be observed that the visceral 
mass, though apparently more coiled, is really less coiled in the 
Helicinidte than in the Xeritidse. In all systematic works stress 
Proc. ZooL. Soc— 1911, No. LIII. 53 
766 PROF. a. C. BOUKNB ON THE 
is laid on the fact that the internal partitions of the shell are 
absorbed in both these families. This absorption has not pro- 
ceeded quite so far in the Neritidse as in the Helicinidse. In 
Nerita and Paranerita there is a recess in the upper right-hand 
part of the shell which contains that lobe of the visceral mass which 
consists wholly of liver and gonads and represents the visceral 
spire of other Crastropods. This recess and the lobe of the 
visceral sac corresponding to it are not found in the Helicinidfc : 
the wall of the oesophageal division of the stomach comes very- 
near to the surface (PI. XXXIII. figs. 17 & 18), and the liver and 
gonads are disposed at the sides of and above the pyloric division 
of the stomach. The more coiled appearance of the whole is 
due to the elongation of the post-tentacular and dorsal regions, 
not to the retention of a larger section of the visceral spire of the 
presumed gastropod ancestor than in the Neritidse. 
From what precedes, it follows that most of the peculiarities of 
the Helicinid organization are the result of excessive growth and 
elongation of a particular region of the body, and it is an 
interesting confirmation of the correctness of the above account 
of the manner in which the Helicinid organization has been 
derived from the Neritid that, if one makes a plasticine model 
of the stomach, kidney, rectum, and intestinal coils as they occur 
in Paranerita, and then rotates the stomach in the manner 
described, the intestinal coils assume very nearly the position 
foimd, with more or less variation in detail, in all Helicinids. 
After this general explanation of the mutual relations of the 
principal viscei-al organs in the Helicinidae, I need only refer to 
particular features in the several systems of organs which I have 
to describe in detail. Before proceeding, it should be put on 
record that there is not a rudiment of the ctenidium in the 
Helicinidse, and I cannot even find a trace of an osphradium. 
The cephalic penis, characteristic of the males of the Neritidpe, is 
also absent, and there is no external diiference between the males 
and females in any of the species that I have examined. 
The Alimentary Tract. 
The complex of organs formed by the buccal cavity, the pharynx, 
the oesophagus with its smaller and larger glandular annexes, the 
radula, the radular sac, and the odontophoral cartilages and their 
muscles, can only be studied by dissection, and this is by no means 
an easy task in animals so small as most species of Helicinidae are. 
The relations of the various organs to one another are far too 
complicated to trace out in sections. The following description 
applies chiefly to Alcadia palliata and A. hollandi, but will serve 
almost equally Avell for any of the other species that I examined, 
for all are very much alike except for the details of the radular 
teeth. 
The mouth is a gaping circular orifice, situated at the extremity 
of the downturned snout: it is surrounded by folded muscular lips. 
MORPHOLOGY OF THE HELICINID^. 767 
The buccal cavity occupies the snout, in front of the tentacles. 
It is a simple funnel-shaped cavity bounded by a rather thick 
muscular wall, the internal sui-face of which is thrown into about 
19 or 20 longitudinal folds. The cavity is lined by a layer of 
rather long columnar epithelial cells which secrete a thick cuticle. 
Dorsally the buccal cavity is prolonged backward into a little 
glandular diverticulum which lies above the median part of the 
cerebral commissure. The buccal cavity is separated from the 
pharynx by a constriction, deepest on the dorsal side, where the 
cerebral commissure lies in it. In a surface view, before dis- 
tui'bance of the various parts, this constriction is not visible 
from above, as it is covered over by the anterior salivary glands 
shortly to be described, and muscle-fibres pass from the walls of 
these glands to the walls of the buccal cavity and of the snout. 
Consequently the cerebral commissure seems to be embedded in 
the buccal mass. 
The passage from the buccal cavity to the pharynx is narrow. 
The pharynx is a relatively spacious sac, of which the cavity 
is continued posteriorly into the oesophagus above and into the 
radular sac below. Beneath and at the sides of the anterior 
end of the radular sac lie the odontophoral cartilages, the 
anterior ends of which pi'oject forward into and occupy the 
greater part of the lower moiety of the pharyngeal cavity. It 
will readily be understood that, in consequence of the projec- 
tion of the anterior ends of the odontophoral cartilages into 
the pharyngeal cavity, the latter extends round them both at 
the sides and below. Below the cartilages the pharyngeal 
extension forms a broad flattened diverticulum, reaching back 
nearly to the posterior ends of the anterior cartilages, as far 
as the point marked x in fig. 3 (PI. XXX.). Latei-ally, the line 
of attachment of the pharyngeal wall to the anterior odonto- 
phoral cartilages is roughly indicated in the same figure by the 
curved line running upward and forward from the point x towards 
the opening of the oesophagus. It results from this arrangement 
that in an oblique section, such as is represented in fig. 4 
(PI. XXX.), the pharynx appears to give oW two posterior diver- 
ticula, lying outside the anteinor ends of the odontophoral 
cartilages. The inner walls of these diverticula are thin and 
composed of a single layer of cubical epithelial cells : they are 
continued round the anterior and upper edges of the cartilages 
into the lining membrane of the radular sac. The outer wall of 
each diverticulum is strengthened by a thin plate of cartilage, 
too small and transparent to be recognized in dissection, but 
readily recognizable in sections. These lateral pharyngeal carti- 
lages serve for the attachment of muscles, one set of which run 
forward to be inserted on the walls of the snout, the other set 
run backward and are inserted on the odontophoral cartilages ; 
the former are protractors, the latter retractors, of the walls of the 
pharynx. 
A portion of the epithelial lining of the outer wall of each 
53* 
768 PROP. G. C. BOURNE ON THE 
diverticulum is composed of very long attenuated epithelial cells, 
among which are long club-shaped glandular cells. This glandular 
stiip may be traced upward and forward to the thickened lip of 
the oesophageal opening, where it forms a prominent ridge 
which passes above into the anterior pair of salivary glands, to 
be described shortly. 
As is shown in PL XXX. fig. 2 and in the section drawn in 
fig. 4, the radular sac opens into the pharynx by a widely gaping 
aperture situated in the trough- shaped depression between the 
anterior ends of the anterior odontophoral cartilages. Posteriorly 
the radular sac passes between the posterior odontophoral cartilages 
and runs at first to the right of and below the cesopha,gus, but 
soon mounts upwards and to the left, the two organs, oesophagus 
and radular sac, being twisted round one another as shown in 
fig. 2. The radular sac is short in Alcadia palUata and is of no 
great length in any of the species that I have studied. The greater 
or less length of the radular sac appears to be an individual rather 
than a specific character. The charactei'S of the radular teeth will 
be dealt with in a separate section. 
The odontophoral cartilages were described in some detail by 
Isenkrahe for Helicina titanica, and I have but little to add to his 
account. A ventral view of these structures in Alcadia jmlliata 
is given in PI. XXXI. fig. 5, and a sketch of a dorsal view of the 
same structures in Eutrochatella pidchella in fig. 6 : both figures are 
drawn to the same scale. As may be seen from the specimens 
figured, the odontophoral cartilages exhibit specific diffei-ences in 
relative size and proportion, but these differences are of too slight 
and elusive a chaiacter to be expressed in a description, and scarcely 
important enough to make it worth while to give a separate figure 
for each species examined. The essential structure is the same 
in all. There are two pairs of cartilages, an anterior and a 
posterior. Each member of the anterior pair is a plate having 
the form of a more or less elongated isosceles triangle ; the 
margins of the plate are thickened and rounded, the central 
portion remains thin. The plate is bent in such a way that its 
lower margin is bent inward posteriorly and its upper margin 
outward. The posterior margin or base of the triangle, forming 
the articular surface for the posterior cartilage, runs obliquely 
from above downwards and inwards. The lower mai'gins of the 
two cartilages are connected by a tough fibrous band, and their 
thickened edges serve for the attachment of the intrinsic and 
extrinsic odontophoral muscles. The posterior cartilages are 
short conical masses ; their apices directed backwards ; their 
ventral surfaces convex and their dorsal surfaces more or less 
concave. Their bi-oad anterior ends are shaped to correspond with 
the articular surfaces of the anterior cartilages, and the two are 
firmly held together by musculai- fibres, whose arrangement is 
indicated in fig. 5. It follows from the above description that 
the odontophoral cartilages form the sloping sides of a V-shaped 
trough, the concavity of which looks upwards and supports the 
MORPHOLOGY OF THE HELICINIDiE. 769 
anterior part of the broad raclular ribbon. The median and 
admedian radular teeth lie in the floor of this trough, the great 
lateral teeth lie in the angles between its floor and sides, and 
the uncini form curved rows running upwards and backwards 
along its sloping sides. The radular ribbon is attached by strong- 
muscular bands to the cartilages. These muscles run obliquely 
forwards from the radula to be attached to the anterior cai'tilage 
of either side, and obliquely backwards to be attached to the 
posterior cartilages, these two sets of muscles causing the ribbon 
to slide forward and backward over the smooth surfaces of the 
ca,rtilages. 
The relation of the oesophagus to the radular sac and odonto- 
phore is shown in fig. 3, which is a drawing of a dissection of 
these structures in Alcadia palliata. The left oesophageal pouch 
and the left side of the oesophagus have been cut away, and the 
roof of the oesophagus has been lifted back to the right side to 
show the entrance to the right oesophageal pouch and other 
structures. In the angle of the deep fold between the oesophagus 
and radular sac are seen the buccal ganglia (g.bicc.) lying just above 
the middle of the anterior odontophoral cartilages. The opening 
of the oesophagus into the pharynx, situated just in front of and 
above the buccal ganglia, is irregularly funnel-shaped, with thick- 
ened and folded lips projecting forward into the pharyngeal 
cavity. Laterally, these lips are deeply grooved, and on either 
side the groove is continued backward and downward into the 
lateral pharyngeal diverticulum described above, and upward and 
somewhat forward into the anterior salivary gland of its own 
side. These anterior salivary glands are formed by a pair of pocket- 
like forward projections of the oesophagus, which in their natural 
position lie side by side and form a pair of pouches lying above 
the cerebi^al commissure. Between them is an anterior ctecal 
diverticulum continuous behind with the median dorsal groove of 
the anterior part of the oesophagus. When separated by an 
incision in the mid-dorsal line and turned outwards, the anterior 
salivary glands present the appearance shown in fig. 2. Inter- 
nally their walls are raised into a number of thick glandular 
ridges : the outermost of these ridges is specially thick and is 
continued downward, in the groove passing to the side of the 
oesophageal orifice, into the glandular ridge on the outer wall of 
the phaiyngeal diverticulum, as has been described above. 
The anterior section of the oesophagus, lying above the 
odontophore, is fairly wide. Internally, its walls present a 
number of longitudinal glandular ridges, and in the mid-dorsal 
line there is a deep groove bounded internally by prominent 
ridges ; posteriorly this groove shallows and eventually dies out. 
On either side of this anterior section of the oesophagus is a 
gaping oval orifice (figs. 2 & 3, o.ce.p.) leading into the large 
oesophageal pouches, or, as some would call them, the posterior 
salivary glands. The last-named structures are capacious irregu- 
larly lobulated sacs with large cavities. Their inner walls are 
770 PROF. G. C. BOURXE ON THE 
lined throughout bv a glanJuhir epithelium, consisting, as far as 
I was able to detevniine, almost -wholly of very long goblet-shaped 
secretory cells containing zymogen granules, with very few attenu- 
ated supporting cells lying between. The histological chai-acters 
of the epithelium were not, however, very well preserved in any 
of my specimens. The two pouches are closely pressed against 
the sides of the cesophagus, and in the species in which they are 
longest follow the turns of the latter. Hence, as the oesophagus 
makes a turn towards the left before it passes down through the 
loop of the rectum, the right oesophageal pouch generally passes 
over to the left side and above the a?sophagus, the left pouch 
passing to the right and below the cesophagus and radular sac. 
The oesophageal pouches are relatively short in Alcadia paUiata 
and of appi'osimately equal width throughout, but they are much 
longer anol oiiminish in diameter towards their posterior extre- 
mities in A. koUandi. They are particulai4y long anoi of a deep 
chocoilate colour in Palceohelieina idee ; in most species they are 
white in spirit-specimens. 
Behinol the openings of the oesophageal pouches the oesophagus 
narrows somewhat abruptly in diameter ; the glanolular internal 
longitnoiinal riolges disappear, anol are replaceol by nine or ten 
longituoiinal ridges formeoi by columnar ciliated epithelial cells, 
and these may be traced throughout its coui'se to the stomach. 
This course is a long one, for the stomach lies aslant on the 
lower side of the viscei-al mass, below the greater part of the 
lobes of the liver and below the coils of* the intestine. As seen 
from above and behind, it is a large pyriform sac, the narrower 
end lying just above the posterior corner of the pericardium ; 
the broader end forming on the right side of the visceral mass a 
large rounoled prominence which fits into the concavity on the 
ventral siole of the i-ight columellar muscle. The oesophagus 
enters the stomach on the upper side o^f its broader end. anol its 
course in the several species examineol will be hiest unolerstoooi by 
reference to PL XXXII. figs. 10 to 15. Passing to the left as it 
enters the visceral mass, the oesophagus lies above the first coils 
of the rectum, then passes below the recurrent coil of the rectum, 
and so arriving at the oiorsal surface of the stomach runs along 
the latter as a flattened tube anol opens, as stated above, into 
its broaoier end, oiUating considerably just at its point of entrance. 
This dilatation, which might almost be described as a diver- 
ticulum of the stomach itself, receives right and left the wide 
oiucts of the liver (PL XXXI. fig. 7, and PL XXXII. fig. 16. li.d.). 
The internal structure of the stomach is very complicated. It 
attracted the attention of Isenkrahe. who gave a fairly accurate 
description of it. Fig. 7 is a representation of a dissection of the 
stomach maole from behind anol below the visceral mass. The 
cesophagus is shown at ce., and its entrance into the stomach is 
indicated by the aiTow. The entrance of the left liver-duct is 
shown at li.d. ; that of the right liver-oluct lies on the far siole 
©f the prominent curved ridge guarding the entrance to the 
MORPHCiLOGY OF THE HELICIXID^. 771 
fesopliagus. Botli the oesophageal aperture and those of the liver- 
ducts aie surrounded by complicated epithelial ridges, which, as 
shown in the drawing, converge towards and pass into a deep 
groove running along the dorsal side of the narrower pyloric 
moiety of the stomach. The edges of this groove are bounded by 
two prominent folds ; that on the right side (the left in the 
di'awing) being continued towards the oesophageal opening as a 
projecting ridge, ending at the side of the aperture in a very 
prominent crescentic projection covered by a thick iridescent 
cuticle. 
The internal surface of the stomach Ls lined by a mixed glan- 
dular and ciliated columnar epithelium, the characters of which 
are shown in PI. XXXI. fig. 8 ; the glandular elements predominate 
in the oesojjhageal, the ciliated elements in the pyloric, moiety of 
the stomach. The epithelial cells are lower in the furrows, taller 
and more slender in the ridges, these latter structures being 
formed entirely by thickenings of the epithelium, and not by 
foldings of the wall of the stomach. The cre.scentic projection to 
the right of the oesophageal opening is formed by a local modifi- 
cation of the epithelium, the cells of Avhich are here extraordi- 
narily long, with nuclei placed about the middle of their length, 
and with apparently homogeneous transpjarent cytoplasmic contents 
(PI. XXXT. fig. 9) ; they are all of one kind, without any admix- 
ture of glandular cells, and, so far as one can judge, they are not 
themselves glandular. The free ends of these cells are covered by a 
very thick and tough cuticular coat, which stains deeply in haema- 
toxylin, brazilin, and other ordinary dyes. Tlie whole structure 
corresponds to the " fleche tricuspide," of which the characters 
have been thoroughly described for Lamellibranch stomachs, 
and which has been noted as occurring in several (gastropod 
'stomachs. There is no definite crystalline style in Helicinidse, 
but in several specimens that I dissected I found the cavity of 
the stomach filled by a semitransparent gelatinous mass, which 
appeared to be similar in origin and composition to a crystalline 
style. In several specimens I found that the intestinal end of 
the groove of the pyloric moiety of the stomach wa.s occupied by 
closely compacted fa'cal pellets or rods, while the cavity below 
was filled either by the gelatinous mass above mentioned or by a 
loose mass of semi-digested food. It may be inferred from this 
that digestion is efi'ected in the general cavity of the stomach, 
and that the indigestible materials of the food are collected into 
the dorsal groove and passed into the intestine. 
Morphologically, the .stomach of the Helicinidse closely resembles 
that of the Xeritidte, and fuiiiher bears a resemblance to the 
stomachs of the Fi-ssurellidse and Scissurellid*, which, as in this 
case, have a groove leading from the hepatic ducts towards the 
intestinal end of the .stomach, but no spiral csecum. 
The small intestine is a comparatively narrow tube, which after 
leaving the pyloric end of the stomach r\ins back for a short 
distance over the dorsal surface of the latter, parallel with the 
772 PROP. G. C. BOURNE OX THE 
oesophagus, and then turning upwards and forwards describes one 
or more convolutions before it passes into the large intestine. 
The small intestine can always be distinguished by its white 
colour and narrow diameter ; it A^aries considerably in length in 
dijSerent species, being \ongest in Alcadia palliaia a.\K\ Orobophcaia 
ponsonhyi, shortest in Euto'ochatella pulchella. Internally it is 
lined by a columnar ciliated epithelium containing a few gland- 
cells, and its internal surface is increased by a well-marked 
internal ridge or typhlosole formed by long ciliated cells. The 
small intestine passes abruptly into the large intestine, the latter 
being of much lai'ger diameter and having pigmented walls. In 
all species of Alcadia and Helicina examined, the large intestine 
runs forward and to the left below the oesophagus, then bends 
abruptly back, forms a wide cix'cular loop w^hich passes above the 
oesophagus, in front of the anterior end of the stomach and along 
the inner wall of the anterior end of the pei'icardial cavity: it then 
turns downwards and to the right, passes right round the lower side 
of the stomach, and mounting upwards again behind it runs in the 
right side of the roof of the mantle-cavity to open by the anus, 
opposite the right tentacle. In the first part of its course, i. e. in 
the short length between the small intestine and the recurrent 
circular loop, the large intestine is lined by very evenly disposed 
columnar ciliated cells, among which I could not detect any 
gland-cells, and this part of the intestine is not, as a rule, full 
of faecal matter. This section of the intestine may be described 
as the large intestine propei', to distinguish it from the rectum, 
into which, however, it passes without any obvious line of 
demarcation. The i-ectum is always full of fsecal debris, and its 
epithelium consists of (1) columnar ciliated cells ; (2) goblet- 
shaped gland-cells filled with coarse granules which stain deeply 
in hgematoxylin and are therefore probably mucinogenous ; 
(3) smaller gland-cells containing small yellow gi-anules. There 
is no typhlosole either in the large intestine or the rectum. 
Noticing that the coils of the gut differed in the different 
species, I have been at some pains to work out this character in 
detail, and figs. 10 to 15 (PI. XXXII.) show the coils charac- 
teristic of six different species. An examination of the figui'es 
will give a better idea of the differences than any description. 
It will be noticed that there are three main types. In Alcadia 
palliata, A. hoUandi, OrobopJiana ponsonhyi, and Palceohelicina 
the intestinal coils, though differing in detail, are alike in this 
respect, that the small intestine runs back more or less parallel 
to the oesophagus over the dorsal surface of the stomach, and 
the large intestine makes abend to the right below the oesophagus 
and then, turning back on itself, makes a second bend to the 
right above the oesophagus. The second type of arrangement 
is shown in Lucidella aureola (fig. 14). In this species the 
oesophagus is not pressed against the dorsal surface of the 
stomach, but runs obliquely down to it ; the small intestine 
passes forward from the pyloric end of the stomach, crosses over 
MORPHOLOGY OF THE HELICINID^. 773 
the oesophagus, and curves round it till it nearlj- touches the 
pyloric end of the stomach again ; here it passes into the large 
intestine, which turns sharply back, passes round the oesophagus 
again, and coming to the sui'face sweeps round to the left in front 
of the anterior corner of the pei'icardium to form the descending 
loop of the rectum. This type is easily derived from the first by 
the shortening of both the small and the large intestine, in 
consequence of which the former is hooked round the oesophagus 
and one of the bends characteristic of the first type is suppressed. 
The third type, seen in EiUrochatella ^mlcliella (fig. 15), difi'ers 
considerably from the other two. The small intestine is even 
shorter than in Lucidella, and the loop formed by the large 
intestine and the first section of the rectum lies wholly on the 
dorsal side of the oesophagus ; this condition is clearly due to 
the gut being much shorter than in the other types, and it 
appears to be quite a constant feature in Eutrochatella. The 
intestinal coils of Aphanocorda andmnanica are singularly like 
those of Eutrochatella. 
I may appear to be giving an undue amount of attention 
to characters of no obvious morphological or physiological 
importance, but it is just because they may be claimed to be 
of importance in the economy of the species that I have spent a 
considerable amount of time in working out these details. Each 
species seems to have a characteristic arrangement of the coils 
of the intestine, and the arrangement is remarkably constant in 
individuals of the same species, allowance being made for 
displacements due to the greater or less state of contraction of 
the specimens. Closely allied species, such as Alcadid palliata 
and A. hollandi, have a very similar arrangement, yet sufficiently 
diff"erent to allow one to recognize them at a glance after 
obtaining some familiarity with their anatomy. Lucidella and 
Eutrochatella, both separated from Alcadia and from one another 
by distinctive characters of shell, operculum, and radula, diffei- 
in a nearly corresponding degree in the coils of the intestine. 
Orohophana and Palceohelicina are Pacific foi-ms which must 
have been derived from American Helicince, the latter being 
closely related to Alcadia., and they resemble the last named in 
the coils of the intestine. To this extent it may be claimed that 
two, three, or more characters vary together in these genera ; but 
Aphanoconia presents a difficulty, for this genus is far removed 
from Eutrochatella in shell and radular characters, and is in these 
respects closely related to Palceohelicina, 3^et its intestine is as 
nearly as may be that of an Eutrochatella. As the two genera 
cannot possibly stand in close genetic relationship to one another, 
the similarity in the pattern of the intestinal coils must be due 
to parallelism, similar causes producing similar deviations from 
type in the two organisms. It has been shown that the 
differences in pattern are attributable to differences in the 
length of the large and small intestines, and this is probably 
connected with different forms of food. As we are ignorant of 
774 PKOF. G. C. BOURNE ON THE 
the habits of the various species of Heliciniflse, and do not even 
know for certain whether each or any species is restricted to a 
particular kind of food, it would be rash to speculate on this 
question, but such evidence as I have collected does seem to show 
that such apparently trivial characters as the coils of the intestine 
are of some physiological importance, and are therefore subject to 
the action of natural selection. 
The Codom. 
The coelom is represented by the pericardial cavity, which, 
although it is of much smaller extent and less complicated than in 
the Neritidae, is nevertheless a cavity of relatively considerable size, 
as may be seen by an inspection of figs. 17 to 20 (PI. XXXIII.). 
As is shown \\\ fig. 1 (PI. XXX.) it comes close to the surface of 
the left side of the visceral mass, and extends forwards neai^y 
as far as the posterior end of the left columellar muscle and 
backwards round the lower side of the viscei'al mass as far as the 
end of the mantle-cavity. It is bounded externally by the very 
thin body-wall, posteriorly by the inner wall of the mantle- 
cavity, internally by the kidney (figs. 17 to 20). At abovit the 
middle of its length it is a cavity of considerable depth, extending 
some way into the visceral mass below the pyloric division of 
the stomach. The reno-pericardial canal, which will be described 
in connection with the kidney, opens into its right posterior wall, 
at some little distance from its hindermost end (fig. 19); other- 
wise it is a closed sac containing the auricle and ventricle of the 
heai't, and does not require further description. 
The Hcemoccele, Circulatory and Respiratory Systems. 
The blood-vascular system, as in all Molluscs, consists partly 
of large lacunar spaces, which collectively are known as hsemocoele, 
and partly of vessels with definite walls. The hsemocoelic spaces 
svirround the viscera, and there is a specially large lacunar space 
below the buccal bulb, in which lie the pleuro-pedal ganglia. 
In the visceral mass and in the dorsal region of the body the 
hsemoccele is largely filled up by the peculiar form of connective 
tissue which I have previously described (2, p. 861) as metabolic 
tissue. In the Helicinidfe the tissue is of precisely the same 
nature as in Neritidae, and it is not necessary to describe it again. 
It evidently consists in large part of reserve tissue, for it is most 
abundant in immature specimens in which the gonads and 
gonaducts are but slightly developed, and is much less abundant 
in sexually mature specimens. This metabolic tissue is specially 
concentrated round the larger blood-vessels. 
It is not possible to trace the course of the blood-vessels by 
dissection of spirit -pi^eserved specimens and only the larger vessels 
can be traced in sections. The following account of the 
circulation embodies as much information as I have been able to 
MORPHOLOGY OF THE HELICINIDiE. 775 
obtain by reconstruction of sections. The ventricle is continued 
forward into a short and wide aorta, which immediately after 
passing through the pericardial wall — which it does at about the 
level of the hinder end of the left columellar muscle — divides 
into three principal branches. The one passes to the right 
towards the stomach, and, entering the visceral mass, divides 
into a number of branches which are distributed to the stomach, 
the intestine, the right lobe of the liver, the gonad, and the 
hypobranchial gland and gonaducts. The left branch runs 
forward for a short distance and then turns downwaxxl into the 
visceral mass and chiefly supplies the left lobe of the liver. 
A branch is directed towards the posterior part of the left 
columellar muscle. The third vessel is an almost direct forward 
continuation of the aorta and runs up in the dorsal region of the 
body towards the resophagus ; it passes above this organ and runs 
over the surface of the radular sac, to which organ it becomes 
firmly attached at about the level of the hind end of the 
pharyngeal bulb. Here it passes into a number of lacunar 
passages, supplying the pharyngeal bulb and the oesophageal 
pouches, and eventually makes communication with the large 
blood-space surrounding the nerve-centres of the head. This 
space in turn communicates freely with the lacunfe surrounding 
the pedal nerve-chords. 
In this labyrinth of blood-channels I have not been able to 
recognize those by which the blood is collected and brought back 
from the various organs to the organ of respiration, the mantle. 
The principal hfemocoelic spaces or blood-sinuses are the 
following: (1) a pedal sinus, surrounding the pedal nerve-cords ; 
(2) a suboesophageal sinus, undei-lying the buccal mass and 
oesophagus ; this is continued back into (3) a circum-intestinal 
sinus, in which lie the coils of the intestine, and the posterior 
pai't of the radular sac ; (4) a peri-gastric sinus surrounding the 
stomach ; (5) a i-ecto-genital sinus, running the whole length of 
the rectum and gonaduct. The last named is evidently the 
pulmonary vein of Isenkrahe (" langs des Darmes zieht sich die 
Lungenvene hin "), but it does not carry back blood from the 
mantle to the auricle. On the contrary, it is easy to see that 
blood passes from it to the numerous fine blood-vessels or 
rather blood -spaces, for they have no definite walls, in the roof of 
the pulmonary chamber. The efierent pallial vein that collects 
blood from the mantle and returns it to the heart is on the opposite 
or left side of the mantle-cavity. It is a direct continuation of the 
auricle and can easily be traced forward in the left corner of 
the mantle-cavity, running along the upper border of the left 
columellar muscle (PI. XXXII. fig. 16, v. pal.) nearly as far as 
the thick muscular anterior border of the mantle. It receives 
nvimerous vessels from the mantle, especially in the anterior 
part of its course. The blood from the intestinal and perigastric 
sinuses does not pass straight to the mantle, but is collected into a 
large sinus provided with definite walls (Pis. XXXIII. & XXXIV. 
776 PROF. G. C. BOURNE ON THE 
figs. 19 &. 21, v.ren.), whence it passes by an afferent renal vessel 
to the glandular portion of the kidney. So far as I can ascertain, 
the blood is returned from the kidney to numerous small vessels 
running in the floor of the posterior half of the mantle-cavity, 
and is conveyed from these to the auricle by a distinct vein 
(PI. XXXIII. fig. 20, v.post.) which opens into the hinder part of 
the auricle, and receives in addition blood from the roof of the 
extreme hind end of the roof of the mantle-cavity. There aie 
thus two distinct vessels opening into the aui'icle, the foremost of 
which brings back blood from the roof of the greater part of the 
pulmonary chamber ; the hindmost brings blood that has passed 
through the kidneys, then through the vessels on the floor of the 
pulmonary chamber, and in addition a small quantity of blood 
from the roof of the extreme hind end of the pulmonary chamber. 
The Excretory Organs. 
The topographical relations of the kidney, as compared with 
that of the ISTeritidfe, have already been explained (p. 765). Re- 
garded in detail, the kidney consists of a thick-walled glandular 
portion and a thin-walled non-glandular portion which serves as a 
bladder and urinary duct. The glandular portion is a large and, 
roughly speaking, quadrangular sac lying in the lower part of the 
visceral mass, below the stomach but above and somewhat to the 
left of the lower loop of the rectum. Its posterior and left wall 
fits closely against the pericardium and forms the inner boundary 
of the latter. The two ends of the sac are produced into large 
pockets or recesses, which partly extend round and embrace the 
walls of the pericardium (PI. XXXIII. figs. 18 & 19), and partly 
extend upwards roiand the sides of the pyloric division of the 
stomach (Pis. XXXIII. & XXXIV. figs. 17 & 24). The cavity of 
the sac is spacious, and only partially subdivided by folds project- 
ing inwards from the wall on the pericardial side ; the opposite 
wall is not folded. The renal blood-vessels run in these folds. 
The whole cavity, including the folds, is lined by a uniform 
glandular epithelium consisting of large iri^egularly shaped cells, 
of varying length, their free ends rounded or club-shaped and 
often projecting far into the lumen of the sac. 
The characters of these cells are shown for Alcadia in fig. 22 
and for Lucidella in fig. 23 (PL XXXIY.). In all the other 
species that I have examined the kidney-epithelium resembles 
that of Lucidella ; it is only in Alcadia that the cells are as long, 
irregular, and amoeboid-looking as those drawn in fig. 22. In 
both cases the cytoplasm is clear and distinctly and coarsely 
vacuolated ; the nucleus spherical, vesicular, with a few granules 
of chromatin. The ureter or non-glandular part of the kidney 
arises from the upper corner of the left-hand recess of the 
glandular sac. Its walls are composed throughout of a non- 
ciliated, very low, cubical epithelium, the cells of which are so 
much flattened that they might almost be called a pavement- 
MORPHOLOGY OP THE HELICINID^. 777 
epithelium. The ureter is a widish tvibe which after leaving the 
glandular sac turns back to run round the hinder wall of the 
pericardium, interposing itself between it and the lower sui^face 
of the visceral mass. After passing from the left to the right 
side it mounts upwards again, passes under the reno-pericardial 
canal, and opens into the right-hand side of the mantle-cavity 
by a thick-lipped slit-like uropore. As is shown in fig. 23, the 
mantle-epithelium is invaginated at the lips of the uropore, and 
this invaginated portion is ciliated, but there is no ui^opore-sac 
such as I have described in the Neritidte. 
The reno-pericardial canal (figs. 19 & 22) opens out of the 
lower part of the right-hand recess of the glandular part of the 
kidney, and runs straight into the right side of the pericardium 
opposite the middle of the expanded base of the auricle. The 
canal is short, straight, and narrow, lined by a cubical ciliated 
epithelium, the component cells of which are small and bear no 
resemblance to the very large ciliated cells lining the long twisted 
reno-pericardial canal of the Nei'itidje. The cilia are fine and 
directed towards the kidney. A thickening of the epithelium at 
the pericardial opening of the canal is suggestive of the presence 
of a pericardial funnel. The structure and relations of the kidney 
and the reno-pericardial duct are remarkably uniform in all the 
species of Helicinidse that I have examined. 
The Generative Organs. 
Thiele (10) has shown that the female ducts ai-e monaulic in 
Hydrocena cattaroensis, but diaulic in Helicina ktiharyi. Before 
my memoir on the Neritidfe was published I had discovered the 
diaulic ducts in Alcadia and Euirochatella, but, as I omitted to 
make mention of them in that place, I must yield priority to 
Thiele, whose diagrammatic figure {loc. cii. text-fig. 2) gives a 
coiTect representation of the general relations of the various sub- 
divisions of the ducts. But it is almost impossible to construct a 
life-like picture of such complicated organs from a study of 
sections, and as I have dissected out the gonaducts, both male and 
female, in a number of species and have checked my observations 
by the study of sections, I may be pardoned for again taking up 
the subject and entering into it at some length. From the 
analogy of the Neritidfe, in which family the gonaducts exhibit a 
considerable range of variation, I expected to discover equally 
great diflerences in these organs in the various genera of Heli- 
cinidfe, but have been disappointed. There are difl^'erences, it is 
true, biit they are slight and do not throw much light upon the 
systematic aflinities of the various genera studied. 
The gonads in all Helicinidas lie above and to the right side of 
the liver. The ovaries are follicular, and the follicles open into a 
large thin-walled chamber which in Alcadia and Eutrochatella is 
situated on the right side of the visceral mass, just behind the 
posterior end of the right columellar muscle and in front of the 
778 PROF. G. C. BOURNE ON THE 
muscular partition separating the visceral cavity from the complex 
glandular mass formed by the hypobmnchial gland and gonaducts 
(PI. XXXVI. tig. 32). The ova appear to go through their matu- 
ration-phases in this chamber, as no ripe ova are to be seen in the 
follicles. In Aleadia and Eutrochatella this ovarian chamber is 
sac-shaped and on tiie right side of the body, but in Pacific and 
Oriental species, such as Pahrohelicina idee. Orohophana ponsonbi/i, 
and Aphanoconia gouldiana, the ovarian chamber is produced into 
a wide tiibe which stretches transverselv across the body and 
receives the products of the follicles of a left ovarian lobe, the latter 
being a distinct triangular lobe, projecting from the surface of the 
visceral mass and packed close under the left columellar muscle. 
This lobe is possibly characteristic of Pacific and Oriental species: 
it is absent in Ahrtdia, and scarcely represented in Eutrochatella. 
My specimens of ZucideUa were all male, and therefore I cannot 
say whether it occurs or not in this West Indian genus. The 
female gonaducts of Alcadia hoUandi, which are to all intents 
and purposes identical with those of A. palUata. are depicted in 
PI. XXXV. fig. 25 ; and figs.;30 to 35 (Pis. XXXV. et XXXVI.) 
represent selected sections from a series passing horizont-ally 
through the genital complex of a female of the same species, 
fig. 30 being the uppermost and fig. 35 the lowest of the series. 
Deahng first with the macroscopical charactei's, the following 
organs or parts can be distinguished, and as their shape and 
relative positions are clearly indicated in fig. 25 a detailed de- 
scription will be supei'fluous. (1) The oviduct od. is a very narrow 
duct leading from the ovarian chamber to (2) the dilated or V- 
shaped portion of the oviduct, in which a descending limb (oc?.") 
and an ascending limb {od.') can be recognized. In Alcadia 
the ascending limb is as long and of approximately the same 
diameter as the descending limb : in its lowest third it receives 
the short and narrow duct of a globular receptaculum seminis. 
(3) The oot^'pe. oot., is a long, more or less dilated glandular duct 
running parallel with the rectum in the right hand of the roof of 
the mantle-cavity, and opening into the latter on the right side by 
a relatively narrow aperture on a papilla which lies in a sort of 
shallow cloaca formed by the expanded lips of the rectal opening. 
Into the posterior end of the ootype open : the ascending limb of 
the V-shaped part of the oviduct ; the caecum of the ootype, a sac- 
shaped structure of considerable relative size, which lies parallel 
to and to the inner side of the V-shaped duct ; thii'dly, the short 
and i-ather narrow duct of (4) the vagina, vag. The last named 
is a slender duct ■\\-ith thin walls, opening into the mantle-ca\-ity 
close to the apertiu-e of the hypobranchial gland. It is continued 
posteriorly into a sac, which runs back on the outside of the 
V-shaped duct and ends blindly (this sac has been displaced in 
fig. 25 to show it more clearly, in its natural position it would be 
concealed by the V-shaped duct). It may be called the vaginal 
sac. Comparing these ducts with those of the Xeritidae, parti- 
cularly with Paranerita (2, fig. 60), it is clear that the ootype is 
MORPHOLOGY OF THE HEUCIXIDJl. 779 
homologous in the two forms, as is also the vagina. The vaginal 
sac of Alcadia coiTesponds to the spermatophore sac of Paranerita, 
but in the former genus the duct connecting the vagina with the 
ootype has been shortened to such an extent that it is merely a 
passage between the two. The V-s^haped duct of Alcadia is only 
a modification of the oviduct and has no exact homologue in 
Paranerita ; the position of the receptaculum seminis is also 
somewhat difterent. There is no trace of an oviduco-coelomic 
funnel in any Helicinid. nor is there any representatiA"e of the 
crystal-sac. On the other hand, the c^cum of the ootype is not 
represented in the Xeritidse, for it would be straining homology 
too far to suggest that it is the equivalent of the lower dilated 
part of the ductus enigmaticus. But if the morphological com- 
parison between the female gonaducts of the Keritid?e and 
Helicinidfe is faii-ly obvious, a physiological comparison is by no 
means so clear. In the specimen of A . hoUandi whose ducts are 
drawn in fig. 25 the hinder moiety of the ootype wa^ filled and 
greatly distended by a large mass of spermatozoa held together by 
a coagulable substance, and, as shown in the figure, a string of the 
same mass of spermatozoa and coagulum extended into and filled 
the cfecum of the ootype. The vaginal sac was empty, but the 
receptaculum was full of spermatozoa. Tliis suggests that the 
'• oot3'pe " is the copulatory canal or functional vagina, and that 
the •• vagina " may serve for the passage of the ova into the 
mantle-caA"ity. But the probability of such a conclusion is 
lessened by the fact that in Ajjhanoconia merguiensis and A. 
goiddiana I found the vagina and vaginal sac full of spermatozoa. 
I have not found ova either in the oviduct or in the ootype of any 
of my specimens ; and apparently in the Helicinidse fertilization is 
not effected by means of spermatophores, for I have found no 
ti'ace of such structures. The mass of spermatozoa and coagiilum 
in AlcaAia koUandi caimot be called a spermatophore. The 
evidence as to the function of the several parts being slender, and 
what there is conflicting. I offer no definite theory on the matter, 
but may add that the " vagina " is evidently a distensible duct, as 
it has thin walls, with a veiy feeble coat of cii'cular muscle-fibres, 
but with a number of muscular slips passing from its walls to be 
attached to adjacent organs. On the other hand, the ootype has 
a thick muscular coat, especially in its hinder moiety, and the 
contraction of this muscular coat would expel any contained 
material through the external aperture. 
A comparison of the gonaducts of the seveial genera shows 
certain differences in detail. The female gonaducts of Eutro- 
ehaieUa. a ^"est Indian genus, are shown in PI. XXXV. fig. 26. 
Their arrangement is clearly very similar to that of Alcadia. The 
ascending limb of the V-shaped duct is shorter in Eutrochatella 
and has more the appearance of a direct posterior continuation of 
the ootype. The receptaculum seminis is small and ovoid, but in 
the same position as in Alcadia. The vagina is short : the vaginal 
sac of moderate length. The caecum of the ootype is a Iso^ge 
780 PROF. G. C. BOURNE ON THE 
flattened sac and extends some way behind the posterior end of 
the V-shaped duct. 
Of the Pacific and Oriental genera, Aphanoconia (PI. XXXV. 
fig. 27) most nearly resembles Alcadia and Eutrochatella. The 
descending limb of the V-shaped duct is large ; the ascending limb 
short and scarcely differentiated from the hinder end of the 
ootype ; it bears a relatively large globular receptaculum seminis. 
The vagina is fairly long, and opens b}'- a very short transverse 
duct rather high up into the ootype. The vaginal sac is short. 
There is no cpecum to the ootype. The female ducts are very 
similar in all the four species of Aphanoconia that I have examined, 
differing chiefly in the relative length of the vaginal sac and 
the position of the vagino-ootypal connection. 
On the other hand, Palceohelicina (fig. 28) and Orohophana 
(fig. 29), while resembling one another, differ in some important 
respects fi-om the West Indian genera and from Aphanoconia. 
In Palmohelicina idm the ascending limb of the V-shaped duct is 
wide and scarcely differentiated from the hinder end of the ootype. 
There is no receptaculum seminis, but the ootypal caecum is large, 
bilobed at its extremity, lined by an epithelium of peculiar cha- 
racter, and filled with spermatozoa. It evidently functions as a 
receptaculum seminis. The vagina and vaginal sac are normal. 
In Orohophana ponsonhyi the descending limb of the V-shaped 
tube is unusually long ; the ascending limb very narrow and short, 
and does not bear a receptacLilum seminis. The csecum of the 
ootype is large, bilobed, full of spermatozoa, and in every respect 
similar to that of PakEohelicina. The vagina is long ; the vaginal 
sac leaves it about halfway between its external aperture and its 
connection with the ootype. 
I am unable to give a description of the female organs of 
Lucidella aureola, as all my specimens were males. 
Summing up the above facts, we see that as regards the 
structure of the gonaducts there are two types in the genera dealt 
with. In the first type there is a receptaculum seminis on the 
ascending limb of the V-shaped duct. This type is divisible into 
two sub-types : the one, found in Alcadia and Uiotrochatella, is 
characterized by the lai^ge csecal appendage of the ootype ; the 
other, found in Aphanoco7iia, has no such csecum. In the second 
type, represented in Palceohelicina and Orohophana, there is no 
receptaculum seminis on the ascending limb of the V-shaped duct, 
but this organ is replaced functionally by the modified bilobed 
caecum of the ootype. According to Wagner (12) Palceoheli- 
cina stands nearest to Helicina sensu restricto, and therefore 
nearer to Alcadia than other Oriental and Pacific forms, but in 
the structure of the female gonaducts, Aphanoconia stands nearest 
to Alcadia, but Palceohelicina with Orohophana stand somewhat 
apart. 
The gonaducts of the Helicinidfe evidently undergo great histo- 
logical changes at the onset of sexual maturity. In sections of 
immature females of Alcadia and Eutrochatella the ootype is a 
MORPHOLOGY OF THE HELICINID^. 781 
relatively nari-ow tube lined by a columnar epithelium, in which 
glandular elements are hardly recognizable, and there is a similar 
lack of differentiation of glandular cells in the V-shaped duct. On 
the approach of sexual maturity the epithelium of the ootype is 
enormouslj' thickened, is rich in glandular elements, and is thrown 
into complicated folds ; at the same time, histological changes 
occur in the V-shaped duct. In the breeding-season, when the 
ootype is distended as shown in fig. 25 (PI. XXXV.), the epithelial 
folds of the ootype disappear, the gland-cells have discharged their 
contents, and the epithelium appears shrunken and thinner than 
before. In consequence of these changes, it is difficult to give 
a consistent account of the histological characters of the ducts : 
what follows is based on a series of sections of a mature 
specimen of Alcadia hollandi, in which the tissues, thanks to 
Mrs. Longstaff 's care, are admirably preserved. 
In the distal half of the ootype, that is in the portion mai^ked a 
in fig. 25, the epithelium is moderately long and of the mixed 
glandular and ciliated kind. The ciliated cells are elongate 
columnar, not much attenuated at their bases, their cytoj)lasm 
clear and very finel}^ granular, their nuclei rather large, oval, 
situated rather to the basal side of the middle of the length of 
the cell. The gland-cells are of nearly the same shape, but of 
rather greater diameter than the ciliated cells, their nuclei slightly 
larger, situated nearer the bases of the cells, and the cell-body 
filled with rather small highlj' refracting spherules of a greenish- 
yellow colour in preparations stained with hfematoxylin and eosin. 
The hinder moiety of the ootype — namely, that poi'tion filled with 
the mass of spermatozoa in fig. 25 — shows somewhat diflerent 
characters. The supporting epithelial cells are, as before, columnar 
and finely granular, but of greater length : they appear to have 
lost their cilia over the greater part of the inner wall of the 
ootype and to end distally in rounded and somewhat vacuolated ex- 
tremities, but as I can find cilia in patches this appearance may be 
due to maceration. The gland-cells in this region (PI. XXXVII. 
fig. 36) are not very abundant, but characteristic, and presumably 
mucinogenous as they stain deeply in hsematoxylin. Their basal 
ends, I'esting on the basal membrane, are broad and in each is a 
rather small subspherical nucleus, above Avhich the cell tapers to 
a fine tube filled with a darkly staining granular material : these 
attenuated cell-bodies run between the supporting cells and ter- 
minate in swollen extremities filled with coarse deeply staining 
spherules. Throughout this region of the ootj^pe the epithelium 
is thrown into ridges and furrows, which are partly due to the 
folding of the walls, but chiefly to the unequal length of the 
epithelial cells. At the hinder end the folds increase and there is 
a prominent valve projecting into the lumen and making a com- 
plete spiral turn just above the opening of the V-shaped duct. 
This opening, guarded b}'^ the above-mentioned valve, is narrow. 
The upper part of the V-shaped duct is lined by an epithelium of 
the same character as that of the hinder moiety of the ootype, the 
Proc. ZooL. Soc— 1911, No. LIV, 54 
782 PROF. G. C. BOURNE OX THE 
suppovtiug cells being liei-e distinctly ciliated and the deeply 
staining mucinogenous cells conspicuous. This epithelium is 
thrown into a distinct spiral ridge, which winds round the uppier 
part of the V-shaped duct nearly as far as the entrance of the 
duct of the receptaculum seminis. Here the epithelium changes 
its character ; the deeply staining mucinogenous cells disappear 
and gi\-e place to vevj numerous long tubular gland-cells with large 
oval basal nuclei, the tube-shap>ed cell- body coarsely alveolar and 
the alveoli containing lai'ge refringent non-staining spherules. 
Wedged between these are the ciliated cells, with elongated nuclei 
at about the middle of their length, very attenuated basal ends, 
and somewhat expanded wedge-shaped distal ends, each with a 
distinct striated border and a tuft of fairly long cilia. The i-ecep- 
taculum seminis (PI. XXXTIT. fig. 37) is lined by a low columnar 
ciliated epithelium of uniform character. The cell-bodies are finely 
gi'anular and stain readily ; the nuclei spherical and deeply 
staining. Each cell has a distinct striated border and bears a tuft 
of long coarse cilia. The spermatozoa in the receptaculum are all 
arranged with their heads directed towards the centre, their tails 
outwards and entangled among the cilia of the epithelium. The 
receptaculum and its duct are invested by a very stout coat of 
muscular fibres. 
The ti-ansition from the upper end of the ascending limb of the 
V-shaped duct to the narrow tube of the oviduct is abrupt. The 
oviduct is lined throughout by an epithelium consisting of long 
columnar cells bearing specially long and coarse cilia. Tlie cha- 
racters of these cells are shown in fig. 38 (PI. XXXYII.). 
The cfecum of the ootype is lined by an epithelium difiering 
from that of the rest of the ootype in the absence of glandular cells. 
The walls of the cjecum, like those of the hinder moiety of the 
ootype itself, are provided with a tolerably thick coat of muscular 
fibres, mostly disposed circularly. The muscular coat is not folded, 
but the epithelium is disposed in longitudinal ridges due, as seen 
in fig. 39 (PI. XXXVII.), to the greater length of the cells com- 
posing them : this figure is from Orohophana ponsonhyi and not 
from Alcadia ; in the latter genus the cells ai'e somewhat longer 
and more slender, but otherwise similar in character. As is shown 
in the figure, the cells are club-shaped with rounded ends projecting 
into the lumen of the ciecuni ; they do not bear cilia. It is the 
presence of this characteristic epithelium in the bilobed sac full 
of spermatozoa leading into the hinder end of the ootype in Palceo- 
helicina and Orohophana which leads me to identify the sac in 
question with the caecum of the ootype of Alcadia and Eutrochatella 
rather than with the receptaculum seminis, and it is further to be 
remarked that in the non-ciliated bilobed sac the spermatozoa are 
arranged pell-mell, with their heads and tails in all directions 
instead of being definitely oriented as they are in the ciliated 
receptaculum seminis. 
The distal third of the vagina is lined by an epithelium consisting 
for the most part of highly vacuolated clear cells with basal nuclei, 
MORPHOLOGY OF THE HELICINID^. 783 
and between these ai^e very attenviated supporting cells. I could 
not detect any cilia on the latter. 
The proximal two-thirds of the vagina and the vaginal sac 
are lined by a non-ciliated epithelium of uniform character, the 
details of which were not well preserved in my sections of Alcadia 
and Eutrochatella : apparently they had been injuriously aflected 
by the action of Perenyi's fluid. In Orohojyhana ])onsonhyi the 
epithelial cells of the lower part of the vagina and of the vaginal 
sac are squarish in outline, non-ciliated and clearly glandidar, for 
each contains a number of coarse non-staining spherules. The 
cavity of the sac contains a number of spherules of similar 
character and among them ropy masses of some coagulable sub- 
stance staining faintly in htematoxylin. 
In Orobopliana the epithelial lining of the ootj'pe differs in some 
respects from that described for Alcadia. The supporting cells are 
attenuated towards their bases, have long compressed nuclei 
about the middle of their length, and are distinctly ciliated. The 
gland-cells of the distal part of the ootype resemble those of 
Alcadia, but are apparently differentiated to some extent, for the 
granular contents of those on the inner side of the ootj^e nearest 
the mantle-cavity are eosinophilous, those on the outer side are 
not. Just above the entrance of the vaginal duct the eosinophilous 
cells ai-e replaced by mucinogenous cells staining deepl}' in 
heematoxylin. A large spiral flap or valve separates the opening of 
the caecum from that of the ascending limb of the V-shaped duct. 
The last named is very narrow and invaginated for some distance 
into the terminal part of the ootype : it has no spiral epithelial fold, 
such as is seen in Alcadia. The gland-cells of the distal limb of 
the V-shaped tube are highly eosinophilous. 
Thiele (10) has shown that the female ducts of Hydrocena are 
monaulic. The external aperture leads into a thick-walled glan- 
dular duct, which is clearly homologous with the ootype of the 
Helicinidee. The lumen of this duct is continued posteriorly into 
a fairly wide canal lined b)' a columnar epithelium devoid of 
glandular cells, and this ends in a saccular dilatation of consider- 
able size, which is apparently glandular ; " sein Epithel enthalt 
Kliimpchen von Kornchen." Thiele identifies this sac and its 
duct with the vaginal sac and vagina of Helicina, and regards it 
as the homologue of the right kidney of the Trochidse, which in 
this case has not acquired an independent opening into the mantle- 
cavity. In addition to this sac, three other structures open into 
the hinder end of the " ootype " in Hydrocena : on the right a 
thick-walled glandular c^cum ; on the left the oviduct ; and 
between the two and dorsad of the " right kidney sac " a tubular 
receptaculum seminis. Thiele's homologies seem to be perfectly 
just, and after his discover}'- of the conditions obtaining in Hydro- 
cena, I must agree with him in regarding the vaginal sac of the 
Helicinidpe and the spermatophore sac of the Neritidse as the 
representatives of the right kidney. But I still beg leave to 
differ from his interpretation of the vaginal aperture as the 
54* 
784 
PROF. G. C. BOURNE OX THE 
primitive aperture of the right kidney, and of the external aperture 
of the ootype as a secondarily acquired separate genital duct. The 
conditions in Hydrocena appear to me to be an ample justification 
of the argument put forward in p. 873 of my memoir on the 
Neritidse. Hydrocena is in many respects more primitive and 
therefore more nearly related to the ancestral Neritoid stock than 
the Helicinidse, and Thiele himself points to the generative organs 
as one of the evidences of primitive organization. 
In his memoir entitled " Diesystematische Stellung derSoleno- 
gastren und die Phylogenie der Mollusken " (9) Thiele, after de- 
scribing the male organs of Septaria, gives the following account 
of the male organs of Helicina {^^Waldemaria Wagner) japonica : 
'' Bei Helicina ist der mannliche Geschlechtsapparat merklich 
einfacher, der Samengang ist nur sehr wenig aufgeknauelt und 
weiter, er mundet in den Driisengang von unter und rechts nicht 
weit A' or seinen Hinterende. Der letztere ist bedeutend einfacher 
als bei 2^avicella, durch Falten streckenweise etwas zertheilt, 
doch scheint das driisige Epithel trotz geringer Yerschiedenheiten 
an manchen iStellen in Wesentlichen gleichartig zu sein. Die 
DrUsenzellen liegen dui-chweg zwischen den Stutzzellen. • Dieser 
Gang reicht weit nach vorn in der Mantelhcihle doch habe ich ein 
besonderes Kopulationsorgane nicht wahi-genommen. Die ekto- 
dermale Driise, welche lechts von Hinterende des Driisenganges 
(Prostata) in die Mantelhohle ausmiindet, erstreckt sich, in dem 
sich allmahlieh grosser wird, weit nach hinten, wo sie neben dem 
Hinterende der Niere aufhcirt. Nach ihrem Bau ist an ihrer 
ektodermalen Herkunft nicht zu zweifeln, da sie zwischen den 
grobkornigen DrUsenzellen deutliche Stutzzellen enthalt. Sie mag 
als eine Ai't von Manteldriise ahnlich dei' Hypobi'anchialdriise 
anzusehen sein : ihre Funktion ist unljekannt." 
The ectodermal gland refeired to in this passage I have already 
described as the hypobranchial gland, fully agreeing with Thiele's 
interpretation of it. It has no connection, with the generative 
organs. In the six genera that I have examined the male ducts 
are, with the exceptions to be mentioned hei-eafter, very much 
alike, but not quite so simple as Thiele's description would lead 
one to suppose, and presumably Waldemaria japonica has undergone 
some simplification in these organs, for so accurate an observer 
cannot have overlooked the accessory oigans that I am going to 
describe. 
The testis, like the ovary, is follicular in structure ; fine thin- 
walled ducts converge from the follicles and unite in the I'lght 
side of the visceral mass to form the sperm-duct. The last-named 
organ occupies a position similar to that of the oviduct in the 
female : in immature specimens it is slendei', slightly convoluted, 
and lined by a columnar ciliated epithelium. In mature specimens 
its middle portion is greatly distended by spermatozoa, is consider- 
ably convoluted, and the ciliated epithelial lining is no longei- 
distinguishable. The sperm-duct tapers somewhat and, as Thiele 
describes, opens into the lower and right side of a long glandular 
MORPHOLOGY OF THE HELIOINID^. 785 
thick-vvalled sac, some little distance in front ot" the hinder end of 
the latter. This thick- walled sac, which is evidently the repre- 
sentative of the ootype of the female and of what I have called the 
terminal chamber in the Neritida?, runs forward in the roof of the 
mantle-cavity, below and to the right side of the rectum, and 
opens into the mantle-cavity by a terminal poi-e situated close to 
the anus. At about one-third of its whole length from the 
external aperture, the thick-walled sac — which I shall call the 
terminal sac of the sperm-duct oi-, more shortly, the tei-minal sac 
— is joined by another sac of considerable diameter. This second 
sac, which I shall call the diverticulum, opens into tlie terminal 
sac by a wide apei'tuie, and runs back close to the right side of 
the latter, to end blindly, sometimes just in front of the entry of 
the sperm-duct into the terminal sac [A'phanoconia goiddiana, 
PI. XXXVII. fig. 41) ; in other cases, however, it extends as far 
back as the hinder end of the terminal sac, and may even project a 
little beyond it [Alcadia hollandi, fig. 40). The anterior third of 
the terminal sac, in front of the entry of the diverticulum, exhibits 
three or four deep transverse constrictions : in section it is round 
or oval, and the lumen is partly occluded by deep longitudinal folds 
projecting into it. These folds are covered by a mixed glandular 
and ciliated epithelium : the ciliated cells of tlu^ familiar kind with 
attenuated basal ends, the gland-cells tubular with basal nuclei and 
vacuolated cell-bodies, in Avhich no secretory granules covild be 
distinguished in well-preserved specimens of Eutrochatella. In its 
posterior two thirds the terminal sac is laterally compressed so as 
to be elongate oval in section, and it gives off from each end of the 
oval and fi'om tlie adrectal side numerous short hollow cjecal out- 
growths which are sometimes branched, especially in Ajihanoconia 
(fig. 41). Internally the longitudinal epithelial ridges die out in 
the posterior two-thirds of the terminal sac, but the epithelial 
lining both of the cavity of the sac and of the ctecal outgrowths 
is of very nearly the same character as that of the anterior third. 
The supporting cells are distinctly ciliated. The epithelium of the 
diverticulum difiers from that of the terminal sac only in the fact 
that the gland-cells are full of eosino2:ihilous granules, and the 
cilia of the supporting cells are longer and rather coarser. The 
above characters hold good foi' all the species that I have examined, 
the differences between them being too slight to deserve mention. 
It may be noted that in Alcadia the hinder moiety of the diverti- 
culum is constricted a,t very regular intervals (PI. XXXVII. fig. 40). 
Both in Eittrochaiella and Lucidella I have found in sections a 
second diverticulum in the form of a slender thin- walled tube 
opening into a recess of the terminal sac at the same level as, but 
on the opposite side to, the diverticulum above described. The 
walls of the recess are lined by a glandular epithelium staining 
deeply in eosin. The narrow tube runs back in the mantle-wall 
nearly parallel to the terminal sac and ends blindly just in front 
of the aperture of the hypobranchial gland. Its hinder end 
touches and appears to be adherent to the sub-epithelial muscular 
786 tROF. G. C. BOURNE ON THE 
wall of the mantle-cavity, but there is no apertm^e into the mantle. 
I have not been able to find this tube in other species, but this 
may be due to the imperfection of my sections and to the fact that 
it is too small to be recognizable in dissections. It is a well-defined 
structure in E lUrochatella and is lined throughout by a non-glan- 
dular cubical epithelium. I am inclined to the opinion that the 
anterior third of the terminal sac of the male is the equivalent 
of the body of the ootype of the female ; the diverticulum of the 
male represents the ctecum of the ootype, and the narrow tube 
(PI. XXX \^II. fig. 42, k.r) represents the vagina of the female, 
but has lost its opening into the mantle-cavity. If this iden- 
tification is correct, a relic of the right kidney-sac is I'etained in 
the male, at least in Eutrochatella jjulchella and Lucidella aureola. 
It may be noted that Isenkrahe's drawing of the male organs 
of Helicina titanica is very nearly correct. 
The Nervous System. 
Nobody has given a detailed account of the nervous system of 
any Helicinid since Bouvier dealt with this subject in his 
classical memoir on the nervous system of Prosobranch Gastropods 
(3). In that work he gives an elaborate figure of the nerve- 
centres and principal nerve-trunks of Helicina sagraiana d'Orb., 
and also several figures of the buccal ganglia of the same species 
and of the cei'ebral and pleuro-pedal centres of H. hrasiliensis 
Gray. As is always the case, Bouvier's figures possess a high 
degree of accuracy, and if I have some criticisms to ofi"er, they 
must not be taken as depreuiatory of his excellent work, but 
as an elaboration of it, rendered possible by careful study of 
sections and by the opportunities for exceedingly fine dissection 
afforded by the Braus-Driuier microscope. 
In the first place, it was necessary to determine whether the 
supra-intestinal nerve exists in the Helicinidse. Bouvier had 
failed to find it in the Neritidae, and when in a subsequent memoir 
he announced its discovery in the latter group, he hazarded the 
opinion that it would probably be found in the Helicinidse. 
But it does not exist in these pvdmonate rhipidoglossate.s ; it has 
disappeared in them as completely as the organs with which, 
when present, it is associated, the ctenidium and the osphradium. 
I can speak with certainty on this point, for I have made so 
many dissections and have studied such a sufficient number of 
serial sections that I could not have overlooked it if it were 
present. 
In the second place, I am unable to verify some of the details of 
Bouvier's figure of the nervous system of H. sagraiana. In none of 
the species that I have studied are the pedal, pleural, and subintes- 
tinal centres as distinct as shown b}^ him. As may be seen in 
fig. 44 (PI. XXXIX.), the pleural ganglia are ill-defined swellings, 
scarcely distinguishable from the swollen anterior ends of the 
pedal cords, and the subintestinal ganglion is so intimately fused 
MORPHOLOGY OF THE HELICINID^. 787 
with the pleurals that it is unrecognizable as a separate ganglion, 
even in sections (PL XXXVIII. figs. 45 to 52). The pedal cords, 
though not so widely separated in any of the species of Heli- 
cinidse that I have dissected as in the Neritidae, are not so closely 
approximated as shown in Bouvier's figure. They are fairly 
close togetlier and nearly parallel to one another in Eutrocluitella 
pidchella, somewhat more divergent in Alcadia hollandi, further 
apart in A. palliata, and widely divergent in Aphanoconia 
andamanica. The actual amount of divergence or approximation 
is, however, undoubtedly dependent on the degree of contraction 
of the muscular mass of the foot, and is a character of no great 
importance. If the foot is much contracted the pedal cords are 
approximated and the numerous and slender pedal commissures 
are arched : if the foot is relaxed the cords are further apart and 
the commissures ai^e pulled out straight. I cannot but think 
that Bouvier has exaggerated the length of the cerebro-pleural 
and cerebro-pedal connectives. In none of the sjDecies that I have 
examined are they appreciably longer than the antero-posterior 
diameter of the cerebral ganglia, and in some species, e. g. 
Lucidella aureola, they are very short, but it is, of course, j^ossible 
that they are unusually long in H. sagraiana. In respect of the 
nerves issuing from the ganglionic mass formed by the fusion of 
the anterior ends of the pedal with the pleural centres, Bouvier, 
while otherwise exact, makes one important omission. He does 
not figui'e or describe a relatively large pair of nerves which 
originate one on each side of the most anterior pedal commissurei 
from the dorsal surface of the swollen anterior ends of the pedal 
cords. Each of these nerves (PI. XXXIX. figs. 43 & 44, n.op.) 
passes outwards and backwards, penetrates the muscular wall of 
the body, and passes to the muscles of the operculum, hence the 
nerves in question may be called the opei'cular nerves. That of 
the right side breaks up into a number of fine twigs in the 
opercular muscles, that of the left side gives oflT a stout branch 
which passes to a peculiar hollow organ connected with a plate of 
cartilage near the left corner of the opercular lobe. This organ 
will be described in detail fui-ther on. 
The otocysts are situated just above the origins of the two 
opercular nei'ves, and are therefore on the dorsal side of the pedal 
ganglia, as is shown in fig. 44. Bouvier, describing the otocysts 
of Helicina brasiliensis says " elles sont situees sous les cordons 
pedieux " : and it is true that in a retracted specimen, in which 
the head has been drawn back behind the foot, so that the 
pedal cords appear to lie in front of the cerebral ganglia, one 
does find the otocysts below the pedal cords, when making a 
dissection from the dorsal side. But in such a case the sole of 
the foot is uppermost, and the morphologically doi'sal side of the 
pedal cords is turned downwards, this change of position being 
very puzzling to the observer both in sections and dissections. 
It is worth remarking in this connection that in my experience 
the small Polynesian genera, Aphanoconia, Palceohelicina, and, in 
788 PROF. G. C. BOUHNE ON THE 
a lessei" degree, Orobophana, when they withdraw themselves into 
their shells, do not contract themselves as much as the "West- 
Indian species. The sole of the foot in these Poljaiesian genera 
is longer and narrower than in the West-Indian genera, the 
columellar muscles longer and inserted further back from the 
mouth of the shell. There is therefore more ample room for the 
head and foot in the last whorl of the shell, and when the animal 
retracts itself the foot is scarcely at all contracted, but simply 
slides back with its sole applied to the oviter side of the shell till 
the operculum borne on the broad opercular lobe closes the 
aperture. Specimens of these genera, when extracted from their 
shells, do not present the deformed ajJi^earance of an Alcadia or 
an Eutrochatella, the pedal nerve-cords are not turned forward 
with their morphological surfaces reversed, and if the animals 
were only a little larger they would be much easier to dissect 
than their American congeners. It is possible, and even probable, 
that these different modes of retreating into the shell, which are 
themselves dependent on the varying length and points of 
insertion of the columellar muscles, are correlated with the 
different forms of operculum upon which "Wagner has founded 
his system. At any rate, they are consistent with it, but I have 
not been able to follow out this problem in detail. 
To return to the nervous system. The opei'cular nerves must 
not be mistaken for the parietal nerves correctly described and 
figured b}^ Bouvier and labelled cV , e . The parietal nerves 
(PI. XXXIX, fig. 44, n.jKir.) are much more slender than the 
opercular nerves and originate, as shown in fig. 44, from the 
pleural centres, between the great pallio-columellar nerves and 
the cerebro-pleural connectives. They pass to the muscular walls 
of the head behind the tentacles. From the venti'al side of the 
swollen anterior ends of the pedal cords, in the same cross-section 
as the opercular nerves, a rather stout pair of nei'ves originates 
near the middle line ; these nerves, which ai-e shown in section 
in fig. 46 (PI. XXXVIII.), pass to the pedal gland and appear to 
be specially connected with that organ. 
As regards the subintestinal nerve and its distribution, I am 
unable to bring my observations into agreement with those of 
Bouvier. The short nerve connecting the subintestinal with the 
left pallio-columellar nerve-trunk does not appear to be a constant 
feature. I have found such a connective in a single specimen of 
Alcadia jjalliata, and in that one instance it is much closer to the 
pleuro-pedal centres than is shown by Bouvier. But I can find 
no trace of it in any other specimen that I have examined. I am 
unable to find any trace of the visceral nerve labelled / in 
Bouvier's figure, which he describes as given ofi" from the left side 
of the subintestinal at some distance from the origin of the latter, 
and in general my observations on the subintestinal and visceral 
nerves difier so much from his that a detailed account is necessary. 
The figure illustrating this account (PI. XXXIX. fig. 43) is founded 
upon dissections, and the ultimate ramifications of the principal 
MORPHOLOGY OF THE HELICINID.E. 789 
nei've- branches have been traced in sections. The subintestinal 
trunk in Alcadia palliata^ A. hollandi, and Eiitrochatella pulchella, 
after leaving the subintestinal ganglion, which latter is unrecogniz- 
ably fused into the pleural centres, courses along the floor of the 
anterior division of the general body-cavity, below the pharyngeal 
bulb, the radular sac, and oesophagus. It keeps closer to the right 
than to the left columellar mascle, and on reaching the posterior 
end of the muscle it doubles the angle between it and the visceral 
mass, and entering the latter turns to the left and enlarges to 
form a ganglion of some size fi-om which several nerves are given 
off. That this is a true ganglion-centre, and not a mere nodal thick- 
ening at a point from which several nerve-branches originate, is 
demonstrated by the considerable sheath of nerve-ganglion cells. 
The principal nerves issuing from the ganglion, in addition to the 
main trunk, are the following : — a small nerve, ?/, which passes to 
the right near the surface of the visceral mass and is distributed 
to the gonads and liver. Another small nerve, v\ which passes 
to the left of the visceral mass and appears to innervate the right 
lobe of the liver and' siii'face of the stomach. A stout nerve, 
n.ge)i., which runs to the right, passes above the oviduct or 
sperm-duct, gives off a large branch to the mucous gland, and 
tvirns forward to break up into twigs on the posterior part of the 
complex of genital ducts : this is the genital nerve, and it 
identifies the ganglion from which it originates as the visceral 
ganglion. There is no separate genital ganglion as in the 
Neritidje. The hinder end of the visceral ganglion is continued 
into a. rather stout nei've, which may be regarded as the 
continuation of the main trunk of the subintestinal : this passes 
through the liver and below the smaH and large intestine, and 
turning towards the left it passes towards the lower border of the 
right moiety of the kidney, near which it enlarges to form a small 
but distinct ganglion, which I take to be the representative of the 
elongated visceral ganglion of the -Nei-itid^e. From this ganglion 
small nerves are given ofi' to the liver and kidney, and a larger 
nerve passes below the kidney, skirts the uropore, and can be 
traced beyond as far as the amicle of the heart, at wliich point it 
ceases to be recognizable. It is a matter of exti'eme difficulty to 
follow the above-mentioned nerves through the liver and intestinal 
coils by simple dissection, and I have only been able to make sure 
of their ultimate course by the study of serial sections. 
After this criticism of the general characters of the nervous 
system, I may retui'n to the consideration of some special details. 
The pleuro-pedal centres and with them the subintestinal 
ganglion are, as I have already said, so intimately fused as to be 
practically indistinguishable as separate ganglia. This fusion is 
brought out in a striking manner in sections. Figs. 45 to 52 
(PI. XXXVIII.) represent selected members of a series of nearly 
transverse sections through the pleuro-pedal centres of Alcadia 
hollandi. Fig. 45 represents a section through the pedal cords at 
the point where they begin to diverge from one another. Dorsad 
790 PROF. G. C. BOURNE ON THE 
of them are the otocysts, ot. ; ventrad of them is the pedal gland. 
Each cord consists of a core of nerve-fibres and dendrites surrounded 
by a cortical layer of nerve-ganglion cells. The latter send in 
lateral horns at about the middle of the outer side of each cord 
in such a manner as to divide the central core into upper and 
lower moieties, which have been identified by French authors 
with the pleural and pedal sections of the cords respectively. 
This interpretation, however, does not appear to me to be well 
founded. Fig. 46 represents a section somewhat fuither 
forward than that in fig. 45 ; it passes through the hinder part 
of the anterior pedal commissure, and includes the roots of the 
two nerves of the pedal gland and of the right opercular nerve. 
The nerve-fibres of the former are seen to be supplied from two 
areas of the cortical layer lying respectively on the outer and 
inner sides of the ventral side of the cord. The opercular nerve 
receives its fibres pai-tly from a centre on its own side, partly 
from a centre on the opposite side of the cord, the latter fibres 
crossing over in the commissure. Below them is a stout band of 
commissural fibres connecting the lateral horns of nerve-ganglion 
cells with one another. Above the median ventral raphe is a 
thick mass of nerve-ganglion cells. In a section somewhat 
further forward (fig. 47) the ventral raphe has disappeared and 
the mass of ganglion- cells above it is only represented by two 
small islets of nerve-ganglion cells, which are separated from the 
ventral surface by two well-defined bands of nerve-fibres start- 
ing from the ventro -lateral groups of nerve- ganglion cells and 
passing towards the centre partly decussate, partly sweep round 
the islets to curve rovind to the lateral horns of the ganglion- 
cells. Above these curved bands is the well-defined transvei-se 
commissural band of nerve-fibres, and above this again there is 
on/ either side a centre, consisting of nerve-fibi-es overlaid by a 
layer of ganglion-cells, which is seen to be connected with the 
origins of the opercular nerves. Above the nervous mass a pair 
of muscular cords passing from the otocysts towards the centre 
should be noticed. 
In the next section (fig. 48), taken some little way further 
forward, the two little islets of ganglion-cells lying opposite the 
lateral horns are still visible. Below them are transverse bands 
of commissuial fibres. Between them is seen the most anterior 
part of the decussating tract observed in the previous section. 
After decussation the fibres sweep out right and left to the dorso- 
lateral regions. In the mid-dorsal line is a deep and wide groove 
into which the muscular cords noted in the last section are 
entering. I regard the whole of the sections hitherto described 
as belonging to the pedal centres. The next section (fig. 49) 
shows that the dorsal groove containing the two muscular cords 
has been converted into a canal by the upgrowth and dorsal 
union of the nervous tissue. All that lies below this canal 
belongs to the pedal centres ; all that lies to the sides of and 
above the canal belongs to the pleural centres. 
MORPHOLOGY OF THE HELIClNlD^. 791 
In the pedal centres a prominent bundle of nerve-fibres is 
being formed on either side of the middle line : these when traced 
forvvai'd prove to be the origins of the cerebro-pedal connec- 
tives. Above them are the remains of the transverse anterior 
pedal commissure. Laterally, above the lateral horns of the 
ganglion-cells two other tracts of nerve-fibres are making their 
appearance : these have evidently received large contributions 
from the decussating fibres noticed in the previous sections, and 
when traced forward they pi'ove to form pai't of the cei'ebro- 
pleural connectives. The central canal containing the two muscular 
cords is surrounded by a layer of nerve-ganglion cells, thickest 
on the venti'al side, and above the canal are seen tracts of nerve- 
fibres originating from the lateral horns of either side and passing 
towards the middle line. Above them, again, is a small transverse 
band of commissural fibres, and above these a fairly thick layer 
of ganglion-cells, which, as may readily be seen by comparing 
this with the preceding sections, is something added to what was 
there before, and is, in fact, the layer of pleural ganglion-cells. 
The next three figures (50, 51, and 52) explain themselves. In 
fig. 50 the pedal centres are diminishing rapidly in volume. On 
the left side, which, owing to the sections being somewhat oblique, 
is rather behind the right side, a large tract of vertical nerve- 
fibres is seen passing from the pedal to the pleuiul centres. To 
the outside of this above the lateral horn are tracts of fibres some 
of which run upwards and will pass into the left pallio-columellar 
nerve, others will be continued into the right cerebro-pleural con- 
nective and the right parietal nerve. On the right side the origins 
of the cerebro-pedal and cerebro-pleural connectives are well 
defined. Between them lie the ganglion-cells of the lateral horn, 
and above the nucleus of the cerebro-pleural connective is a second 
lateral ingrowth of nerve-cells, belonging to the pleural ganglion. 
The pleuiul centre of nerve-fibres is well mai-ked, and from it a 
stout band of commissural fibres passes above the central canal to 
the pleural centime of the other side. This is the pleural com- 
missure, which I have already described in Neritidse. Fig. 51 
shows the cerebro-pedal and cerebro-pleural connectives in cross- 
section. The central canal with its contained muscular slips, 
having passed through the ring formed by the pleural and pedal 
centres, emerges as a groove on the ventral side. The origins of 
the right parietal and right and left pallio-columellar nerves are 
clearly visible, and it may be seen that both pleural centres are 
contributing fibres which, passing to the mid-dorsal line, form 
the origin of the subintestinal nerve. It should be observed 
that some fibres from the last named pass dii-ectly into the roots 
of the two pallio-columellar nerves. In fig. 52 the origin of the 
subintestinal nerve is distinct,, and both it and the origins of 
the two pallio-columellar nerves appear to be imbedded in a mass 
of ganglion-cells in which the limits of the right and left pleural 
and the subintestinal ganglia can be traced with the aid of a 
little exercise of the imagination. 
792 PROF. G. C. BOURNE ON THE 
From what precedes, it follows' that the pleuro-pedal centres are 
extremely complicated and are largely composed of definite tracts 
of nerve-fibres, some commissural, some decussating, some passing 
into the nerves issuing from this region. It is noticeable that there 
are several connections of a complex kind between the pleural and 
pedal centres as well as between the right and left pleural centres 
and the right and left pedal cords, and that there are evidences of 
numerous nervous relays throughout the region illustrated. No 
doubt, on analysis, these apparently complicated nerve-tracts can 
be reduced to five groups : (1) the pedal commissure, containing 
both direct and decussating tracts of fibres ; (2) the pleuro-pedal 
connectives ; (3) the cerebro-pedal and cerebro-pleural connec- 
tives ; (4) the pleural commissure, peculiar to the Neritida^ and 
Helicinidje ; (5) the subintestinal connectives, derived from 
both right and left pleurals. Thus, the paths of the nerve-tracts 
might be described as normal, and consistent with our knowledge 
of the usual connections between the chief nerve-centres of 
Molluscs ; but a study of sections will show that the arrangements 
are not so simple as might be inferi-ed from a superficial exami- 
nation of the ganglia and their commissures and connectives. 
For example, it appears that the cerebro-pleural connectives 
contain fibres derived from the pedal centres and that all the 
principal nerves contain fibres derived from two or more areas in 
the fused pleural and pedal ganglion-mass. I have been unable 
to pursue the subject further at the present time, and it is diffi- 
cult to make any further progress because of our ignorance of 
the physiology of the molluscan nervous system. The main 
nerve-trunks must contain both afi'erent and eflferent nerves, and 
it seems evident that these pass to dilFerent areas of the cortical 
layer of ganglion-cells, but as at present we have no means of 
distinguishing between these two kinds of fibres further analysis 
of the details of the nervous system is impossible. It may be of 
use to future workers on this subject to remark that there are two 
kinds of ganglion-cells in the cortical layer: larger cells with 
clear nuclei staining faintly in hsematoxylin, and much more 
numerous smaller cells with deeply staining nuclei. It should be 
possible to trace the connection of the nerve-fibres with these 
different kinds of cells, but such an investigation demands fresh 
material, and could form no part of the present work on the 
Helicinidse. 
As Bouvier found considerable difl:erences in the size and shape 
of the cerebral ganglia in Helicina sagraiana and H. brasiliensis, 
I have studied these centres with care in the hope that I might 
discover characters of classificatory value, but I have been no 
more successful here than I was in the case of the genital ducts. 
The characters to Avhich Bouvier draws special attention are the 
relative size of the cerebral ganglia (enormous in JI. brasiliensis) ; 
the size and shape of the labial lobe ; the origin of the labio-probos- 
cidean nerves, which all spring from the labial lobe in H. brasi- 
liensis, but only one has this origin in //. sagraiana. As regards 
MORPHOLOGY OF THE HELICINID^. 793 
the relative size of the cerebi^l ganglia I find that the proportion 
of each cerebral ganglion to the pleuro-pedal mass is expre>ssed by 
the following figures : — in Alcadia palliata, | ; Alcadia hollandi^ 
+ 1 ; Eutrochatella pidchella, | ; Lucidella aureola, | ; Palceo- 
helicina idee, nearly ^ ; Orohophana ponsonbi/i, 4 ; Aphanoconia 
gouldiana, +| ; A phanocoiiia rogersii, f. The relative length of 
the cex^ebro-pedal and cerebro-plenral connectives varies greatly : 
they are longest in the two species of Alcadia and in Palceo- 
helicina idee ; of moderate length in Orobopka^ia, Ajjhanoconia, 
and Eutrochatella ; extremely shoi't in Lucidella aureola. I have 
counted four labio-prolioscidean nerves on each side with more 
or less certainty in all the species examined with the excep- 
tion of Apjhanoconia rogersii, in ^^'hich there appear to be five. 
Of these, counting fi'om above downwards, the fii-st and third 
are invariably stout nerves wbich brancli soon after their origin ; 
the second and fourth are slender and only divide into blanches 
at their extremities. The labial lobe in all the species at 
my disposal has the form of a rounded boss projecting inwards 
from the antero-inferior edge of the ganglion : the shape and 
relative size of this lobe differ somewhat in the various species, 
but the differences are too slight to express in words. Fig. 53 
(PI. XXXIX.), representing the left cerebral ganglion of Palceo- 
helicina idee, and fig. 54, representing the same ganglion in Alcadia 
palliata, show the extremes of difference in shape observed by me, 
and, on the whole, the cerebral ganglia of the Polynesian species 
T-esemble those of Palceohelicina, those of the West-Indian species 
those of Alcadia. The cei-ebral ganglia of the Helicinidje, wedged 
in as they are between the antei-ior end of the pharyngeal bulb 
and the walls of the head, are nearly flat, the labial lobe projecting 
inwards beneath the pharyngeal bulb. Because of their flatness 
they are very I'eadily stained and mounted as tiunspaient objects, 
and figs. 53 &l 54 give some idea of the complexity of the nerve- 
tracts and centres within the ganglion. One may distinguish an 
ocular centre, which is large relatively to the size of the ocular 
nerve, a tentacular centre, small relatively to the size of the 
tentacular nerve, and a relatively smaller commissural centre. 
Each of the labio-proboscidean nerves has a more or less well- 
defined centre of its own, but the buccal and labial commissures 
have no distinct centres at their origin. There is, further, a 
median lobe which possibly serves as a relay for various nerve- 
tracts running into ami around it. It is evident that the nerve- 
fibres of the cerebro-pleural connective make direct and intimate 
connection with the ocular and tentacular lobes, and that a 
stout band of fibres curves i-ound from the I'oot of the cerebro- 
pleural connective to the base of the labial lobe, receiving on its 
way an accession of fibres from the cerebro-pedal connective. 
This nerve-tract makes connections with the centres of origin of 
the buccal and labial commissures and the labio-proboscidean 
nerves, and a well-defined curved band of fibres sweeps round 
from the origin of the first labio-pi'oboscidean nerve to enter the 
794 PROF. G. C. BOURNE ON THE 
cerebral commissure, the last named also having connections with 
the tentacular and median centres. Evidently, the cerebral 
ganglia have undergone a high degree of concentration and 
integration, but it is to be remar-ked that if the labial lobe as 
figured for Alcadia were pulled out towards the bottom of the 
picture, it would form an elongated labial process from which 
the labio- proboscidean nerves would be given off at intervals, as 
is the case in TrocJms and Turbo. In other words, the labial 
lobe, as it seems to me, is represented, not solely by the little 
projecting boss from which the labial commissure originates, but 
by all that part of the ganglion that lies below a line drawn from 
the lower side of the origin of the cerebral commissure to a point 
just above the origin of the buccal commissure. 
The buccal ganglia, with their commissures and the nerves 
originating from them, have been very cori'ectly figured by 
Bouviei". 
The organ which I have mentioned above as connected with a 
branch of the left opercular nerve is shown in section in fig. 55 
(PI. XL.). It is deeply embedded in the muscular tissue of the 
opercular lobe and lies to the left of the anterior end of the 
lobe close to the origin of the left columellar muscle. It consists 
of a cartilaginous plate of subtriangular form, the edges of the 
anterior apex inrolled ventrally and eventually fused so as to foi-m 
a short conical tube. This cartilage forms, as it were, the cover 
of a flattened sac (fig. 55, sac.) lined throughout by an epithe- 
lium which is thin and composed of a single layer of somewhat 
flattened cells on the side attached to the cartilaginous plate, but 
thick and composed of columnar cells beai-ing short stiff cilia on 
the opposite side. Anteriorly this is continued into the tube 
formed by the inrolled edges of the cartilaginous plate, and here 
the columnar ciliated cells form a nearly continuous lining to 
its cavity. Posteriorly, as shown in fig. 55, the ciliated cells 
forming the floor of the sac (the reader must understand that the 
figure is reversed, so that the ventral side is uppermost) rest on a 
thick basement-membrane, from which a broad band of muscular 
fibres spreads to be attached partly to the muscular wall of the 
left side of the neck, partly to the bands of muscular fibres passing 
over the otocysts. Into this muscular band the large branch of 
the left opercular nerve penetrates. Taking an anterior course 
this nerve gives off a branch to the operculai- muscles, but its 
main trunk is directed towards the anterior tubular end of the 
organ under consideration, and there passes through a small 
perforation in the cartilaginous wall and is distributed to the 
ciliated columnar epithelium lining the cavity of the sac, Dorsally 
the cartilaginous plate is connected with the left columellar 
muscle by a stout muscular band passing obliquely outwards. 
Above this band are seen in fig. 55 the sections of two convolu- 
tions of a coiled glandular tube, which on the one hand commiuii- 
cates by a very narrow duct with the antei'ior tubular end of the 
above-mentioned sac, and on the other hand opens to the exterior, 
MORPHOLOGY OF THE HBLICINID^. 795 
near the left anterior edge of the operculum, between it and the 
membranous flap that surrounds the opercular lobe. This tube is 
lined throughout by a glandular epithelium composed of rather 
tall goblet-cells with deeply staining basal nuclei and clear cell- 
contents. 
If, now, we enquire into the morphological significance of this 
peculiar organ, I think there can be little doubt as to its homology. 
It occupies the same position and receives the same nei've- supply 
as the crypt into which fits the curved process of the opercuhun in 
the Neritid.ie. This process is no longer- to be seen on the 
operculum of the Helicinidse, but from a study of the muscular 
attachments in the two groups I am inclined to think that the 
cartilaginous plate described above represents its inner extremity, 
all direct connection with the operculum being lost. In 
connection with it new structures have been formed, viz. the sac 
and the glandular tube. What its physiological significance is it 
is hard to say. It is clear that, by contraction of the muscular 
bands attached to it, the sac may be widely dilated, and when 
dilated, air must flow into it through the glandular tube. The 
abundant nerve-supply and the character of the columnar epithe- 
lium bearing short stiff cilia suggest that the sac has a sensory 
function, and it is possible that it may be a special sense-organ, 
likely enough of an olfactory character, which enables the animal 
to receive impressions from the external world when retracted 
into its shell. For the opening of the glandular tube is in such 
a position that it would open to the outer air whenever the 
opercular plug was ever so little loosened. 
The pedal gland, an organ which is absent in the aquatic 
Neritidse, is largely developed in the Helicinidse. Its position and 
general structure are roughly indicated in fig. 45 (PI. XXXVIII.). 
It consists of a main duct below the pleuro-pedal nerve-mass and 
extending some little way but not far back below and between the 
pedal cords. The duct is lined by a columnar ciliated epithelium 
raised on the ventral side into two prominent ridges, one on either 
side of the middle line. Suirounding the duct are bunches of 
unicellular glands, which penetrate among the interlacing muscle- 
fibres of this region of the foot. Each unicellular gland is 
prolonged into a fine duct which passes between the epithelial 
cells of the main duct and opens into its lumen. The histology 
of this gland is reminiscent of that of the byssus gland of 
lamellibranchiate molluscs, described by me in another place. 
The main duct opens at the anterior end of the foot, in the mid 
line, below the snout. 
Mention may be made here of the large mucous gland which I 
agree with Thiele in identifying as the hypobranchial gland. It is 
of relatively enormous size in the Helicinida?, but in structuie and 
position does not differ much fi'om what I have described for the 
Neritidas. It opens into the mantle-cavity (PI. XXXY. figs. 28 
& 30) just in front of the aperture of the vaginal duct and, as shown 
in figs. 30 to 35, it forms a considerable glandular mass bulging- 
796 PROF. G. C. BOURNE ON THE 
into the mantle-cavity to the left side of the genital ducts. As 
may be seen in figs. 16-20 (Pis. XXXII. & XXXIII.), it extends 
far beyond the hind end of the genital ducts, accompanying the 
rectum in its course, and lying to the right side of the kidney 
at the hinder extremity of the visceral mass. In the section 
depicted in tig. 20, which passes through the rectal coil at the 
bottom of the hind end of the visceral mass, the hypobranchial 
gland on the right side of the rectum appears to form a pair with 
the kidney on the left, but there is, of course, no relationship 
between the two organs. Throughout its course the hypobran- 
chial gland con.sists of an iriegularly folded flattened sac, from 
which short glandular divei-ticula are given ofi" in all dii'ections. 
In its terminal pait, as is shown in figs. 1 8-20, the gland appears 
to be differentiated into two portions : one lying nearei' the 
oesophageal end of the stomach is lined by an epithelium loaded 
with fine dark granules ; the other portion, lying nearer to the 
mantle-cavity, is lined by an epithelium of the character shown 
in PI. XXXIX. fig. 56. It is made up of large glandular cells, 
oblong in outline, and filled with a highly refracting granular 
substance which, when the cells are ready to discharge their 
contents, is accumulated into oval pellets, as shown in the figure. 
Between the gland-cells are long and very attenuated interstitial 
cells, of which the outer ends ai'e expanded and produced to 
form a cover ovei' the outei' ends of the gland-cells. The nuclei 
of the interstitial cells lie in their expanded outer ends. I could 
find no trace of cilia. In nearly every specimen examined the 
mantle-cavity was full of a sticky gelatinous mass secieted by the 
hypobi'anchial gland. 
From what precedes it is evident that the Helicinida^ are a very 
homogeneous gi'oup, so far as their anatomical characters ai-e 
concerned, and that such differences as I have been able to detect 
are of very little assistance in classification, the resemblances and 
differences in one set of organs suggesting one class of aflSnities, 
those of another set of organs suggesting another class. Thus, 
taking the arrangement of the coils of the intestine as a criterion, 
we should place Alcadia, Orohophana, and Fakeohelicma close 
together, with Lucidella related but somewhat apart : Eutrochatella 
would go with Aphanoconia to form a distinct group. But if we 
took the characters of the female gonaducts as a criterion we 
should get a diffeient arrangement. Eutrochatella would stand 
nearest to Alcadia, with Aphanoconia more distantly related : 
Fakeohelicina with Orohophana would form a distinct group. 
The nervous system is so similar in all the species that it affords 
a very slight guide, but, as far as the cerebral ganglia give any 
clue, the genera would fall into an arrangement consistent with 
their geographical distribution ; Alcadia, Lucidella, and Eutro- 
chatella forming one group ; Palffohelicina, Orohophana, and 
Aphanoconia another. Finally, the radular characters, which 
have attracted a considerable share of the attention of systematists 
and in my experience afford the most reliable and readily 
MORPHOLOGY OF THE JJ ELTCINID^:. 797 
recognizable marks of distinction between diiferent species, 
give a totally difterent I'esult. Taking these as a criterion, 
E'Utrocliatella stands well apai't : the remaining genera show a 
snfficient amount of similarity to justify our placing them in a 
single group, in wliich Palcfohellcina stands nearest to Alcadia; 
Aphanoconia is closely related to Pcdcvohelicina ; Oroho2)hana, 
while showing relationship to the two last named, has distinctive 
characters which keep it somewhat apart ; and Liocidella, while 
showing relationship to Alcadia, has undei-gone modifications 
which, in one feature at an}' rate, resemble those which distin- 
guish Orohophana from Palceohelicina. 
Oa the whole, the radular characters aftbrd the safest clue to 
affinity, agreeing as they do with the conclusions founded on 
conchological characteis and on geographical distribution. 
In all the Helicinida^, so far as is known, the radular formula 
may be represented as oo . 1(3 + 1 +3) . 1 . oo . The Proserpinidfe 
have a somewhat difierent, and the Hydrocenidse a very different, 
formula, biit they need not be considered here. 
As different authors use different names in describing the teeth 
of Neritoid gasti'opods, I must define my tei-ms before proceeding 
further. Of the teetli included in brackets in the formula, I call 
the single tooth in the centre the median, ; the three teeth on 
either side of it the adinedians. The large tooth on either side of 
the admedians 1 call the lateral, and the numerous teeth to the 
outside of these the marginals. In Eutrochatella, as Troschel has 
shown, the lateral teeth are relatively very large and of charac- 
teristic shape, being mushroom-shaped, with the top of the pileus 
hollowed out to form an articular cavity, into which fits the stalk 
of the lateral tooth of the row next in front of it. The edge of the 
pileus is entire. I have attempted in fig. 57 (PI. XL.) to give 
some idea of the veiy complicated structure of this tooth in Eutro- 
chatella fulchella. It should be noted that it has an external 
process, or " Basalanhang," which Troschel described as charac- 
teristic of the genus Helicina. For the rest, this mushroom-shaped 
tooth more nearly resembles in shape the corresponding radular 
tooth in the Neritidse than is the case in any other Helicinid, 
The mai'ginal teeth of Eutrochatella are simply pointed curved 
bars, without denticulations at their free extremities. In the 
genus Helicina Lamarck [nan sensii restricto Wagner) the laterals 
are not pileiform, but consist of a stout median portion which I 
shall call the " stalk" ; from the inner side of this a mox-e or less 
broad aliform plate projects obliquely forward ; the anterior 
border of this plate is thickened, recurved, and bears a number of 
denticulations, varying from 7 to 12 in number in the diffei-ent 
species that I have studied. Attached to the outside of the stalk 
by an imperfect joint is the pointed external process (the 
" Basalanhang " of Troschel), and the top of the stalk is excavated 
to form an articular cavity for the hinder end of the stalk of 
the corresponding tooth in the row next preceding. Also, in all 
species of Helicina the marginal teeth have broadened recurved 
Proc. ZooL. See— 1911, No. LV. 55 
798 PROF. G. O. BOUR>fE ON THE 
anterioi' extremities bearing denticulations. Thus, there is a 
consiclei'able difference between Etitrochatella and Helicina, bnt the 
gap is bridged over by Trochatella clirysochasma, in which, accord- 
ing to Trosche], the lateral tooth is pileiform, but with an oblique 
anterior border beaiing from 7 to 9 denticulations, and whereas 
the proximal marginal teeth are simply pointed as in Etitrochatella, 
the more distal marginals bear denticulations, increasing from one 
to four in number. I have shown that anatomically Eutrochatella 
bears the closest resemblance to Alcadia, differing only in the 
arrangement of the coils of tlie intestine. 
The genus Alcadia is characterized by a notch separating the 
peristome of the shell from the columella. It is stated (Fischer, 
' Manuel de Conchyliologie,' p. 795) that the operculum has a 
dentiform process: I can only say that I cannot find a trace of 
any such structure in J., palliata and A. hollandi. In all other 
respects Alcadia is similar to the point of identity to Helicina. 
Troschel declares that the only recognizable diff'erence between the 
radulas of Alcadia and Helicina is in the form of the median tooth, 
a character of very little value, for, as I shall show, the shape of 
this tooth varies from species to species. But Troschel's figure of 
the radula of Alcadia is not very exact. I have given in PI. XL. 
fig. 58, atof, large scale drawings of the teeth of A. hollcondi :, 
those of A. palliata differ only in minute particulars. Oompaiing 
these Avith the drawings of the radulae of Litcidella, Fala^ohelici'iia, 
Orobophana, and Aphanocoiiia (Pis. XL.- XLII. figs. 59-65), it 
will be seen that the first admedian tooth of Alcadia has a 
characteristic shape, being subquadrangular in outline, with its 
anterior outer angle produced into a knob on which are borne 
four blunt denticulations. The large lateral has a short stalk, 
hardly projecting behind the oiigin of the aliform plate : the 
latter is large, expanded, bearing seven stout but blunt teeth on 
its recurved anterior margin. The ai'ticular excavation is very 
shallow : the external process long and pointed. 
Of the other radulte figiued, those of Falwoheliciva (PI. XLI. 
fig. 60) and Aphanoconia (Pis. XLI. k XLII. figs. 62-65) bear the 
closest resemblance to Alcadia. Both these genera were included 
in Helicina Lamarck, and have only recently been separated by 
Wagner. In them the lateral teeth have the same general shape 
as in Alcadia, but the stalk is longer, the aliform plate less 
expanded, the denticulations on its anterior border vary in size, 
shape, and number. The first admedian tooth is very similar in 
the two genera, and differs from that of Alcadia. The median 
tooth is very variable in size and shape. The similarity of the 
radulse of Pcolceohelicina and Aphanoconia is remarkable, and leads 
one to doubt whether Wagner is justified in placing these forms 
in different genera. On the other hand, Oroho]jhana (PI. XLI. 
fig. 61) is distinct : its lateral tooth is that of Palmoheliciva, but 
the first admedian is relatively large, acutely triangular, its 
anterior border thickened but without denticulations ; it is 
feebly coi-neous and nearly transparent, suggesting that it is in 
MORPHOLOGY OF THE HBLICINIDiE. 799 
course of disappearance. The median tooth is heart-shaped, 
minute, and similar])^ feebly corneous. Lucidella (PI. XL. fig. 59) 
is quite distinct in radular characters : in the lateral teeth the 
stalk is practically obsolete, the bulk of the tooth consisting 
mostl}' of the aliform pi'ocess with its thickened denticulate 
border, which is continued posteriorly into the ai'ticular knob. 
There is no anterioi' articular excavation, but a thin tiiangular 
external piece which serves to support the articular knob of the 
tooth of the row next in front, and for the attachment of the 
external process. The third admedians are of the usual petaloid 
shape ; the second admedians stout, triangular, with a thickened 
curved anterior edge, bearing on its outer surface a small minutely 
denticulate trenchant process. The first admedians are rather 
large, but feebly corneous, with a thickened anterior non -denti- 
culate border ; they have been modified in a manner analogous 
to what has been obsei'ved in Orohophana. The medians are 
broadly heart-shaped, feebly corneous, nearly divided into two by 
a deep median antei'ior notch. 
Summing up these details and taking into comparison Troschel's 
figures, which are mostly of species of Helicina sensu restiicto of 
Wauner, and confining oui- attention to the lateral tooth, which is 
the lai'gest and obviously of most functional importance in the 
Neritacea as well as in the Helinacea, we see that there is an easy 
transition from Etitrochatella to Alcadia : that the lateral tooth 
of Alcadia is of the form characteristic of the Helicinidfe in 
general, but shows a tendency to a reduction of the stalk, which, 
as Troschel has shown, is common to many American and West- 
Indian species. This tendency is exhibited in an extreme form 
by Lucidella. But in the Pacific and Oriental genei-a the stalk 
and the articular excavation connected with it are well developed. 
But the lateral tooth of Eutrochatella bears an extremely close 
resemblance to that of the Neritida?, and there is this further 
resemblance, that the first admedian tooth, which is of veiy large 
size in the Neritidfe, is relatively of much larger size as compared 
with the second and third admedians in Eutrochatella than in 
any other Helicinid. If such characters can be relied upon as a 
guide to affinity, Eutrochatella is the most closely related among 
the Helicinidfe to the Neritoid ancestor of the group. From 
Eutrochatella forms have been derived : on the one hand, the 
Proserpinidfe, which also have a lar-ge pileifoi-m lateral tooth ; 
on the other hand, Helicina. We may infer that the earliest 
Relicince retained the stalk and articular excavation which are 
such mai'ked features in the pileiform lateral tooth of Euti'o- 
chatella and Proserpina. 
The forms which, as suggested in the earlier part of this paper, 
were transported by !■ some unknown means across the Pacific 
Ocean to the Philippines must have possessed these features 
and transmitted them unchanged to their descendants which 
now inhabit the Oriental and Indo-Pacific regions. But in 
America and the West Indies there has been a tendency, more 
800 PROF. G. C. BOURNE ON TEE 
fully realised in some species* than in others, to 'a reduction of the 
stalk and articular cavity, this reduction being shown to a slight 
degree in Aloadia, to a marked degree in Lncidella. 
In all the Helicinidie there is a tendency to the reduction of 
the central and admedian teeth : this tendency is shown in a 
marked degree in Lucidella and Orohophana, but must have 
reached its present degree independently in these two genera. 
The reduction is carried to an extreme degree in Hydrocena, in 
which the second and third admedians have disappeared ; the 
median and first admedian are present, but in a rudimentary 
condition, and the laterals are reduced to mere rods of no great 
size. But I am disposed to think that the Hydrocenidfe must 
have branched oif from the Iferitoid stock iiulependently of the 
Helicinidse. They retain many primitive features, as Thiele has 
shown, among others the process of the opei'culum which is quite 
Neritoid in character, and their geographical distribution favours 
this view. Hydrocena is confined to the marine littoral of 
Dalmatia ; Georissa lives at considerable altitudes on the Khasi 
Hills in India. It is by no means improbable tliat pulmonate 
forms may have been developed more than once from such 
animals as the 'Neritidse, which show a predilection for migrating 
as far as possible out of the watei", and for the rest of it, the most 
that can be said in favour of uniting the Hj^drocenidse with the 
Helicinidfe is that both display strong Neritoid affinities. 
The main result of my researches is to show that in such a 
limited group as the Helicinidse the systematists are justified in 
their methods. The visceral anatomy of all the forms that I 
have examined is strikingly similar, and where deviations occur 
they are contradictory and of uncertain value. Tlie Helicinidee 
appear to have inherited an organization with marked Neritoid 
characteristics, and to have maintained it, with little or no 
change. Presumably that orgaiiization is weTl adapted to the 
somewhat narrow i-ange of the conditions of their existence, and 
any deviation fi-om it has been checked by the action of natural 
selection. But there are a thousand deviations, in all directions, 
among characters which cannot by any stretch of the imagination 
be claimed to be of any importance in the struggle for existence. 
Such characters are the texture and coloration of the shell ; the 
shape of the aperture ; the extent and distinctness of the basal 
callus ; the presence or absence of folds at the aperture of the 
shell ; the presence or absence of a minute notcli, such as occurs 
in Alcadia ; the arrangement of the growth-lines on the opei'- 
culum. It might be said that the operculum is an important 
protective organ and therefore eminently susceptible to the action 
of natural selection. But its function is simply to close the 
aperture of the shell, and this it does equally efficiently in all 
the species that I liave examined, the numbei- of these being 
much larger than the few available for anatomical study. As 
long as the operculum performs this function efficiently minute 
characters, such as the greater or less distance of its nucleus from 
MORPHOLOGY OF THE HELICIKIDJE. 801 
the anterior border, cannot possibly determine the question of 
the death or survival of the animal. The same reasoning applies 
to the variations of the radular teeth : the function of the radula 
is to rasp, and any of the modifications shown in figs. 60 to 65 
is equally efficient as a vAsp. Nobody, I think, would venture 
to assert that the minute difli'erences in the four species of 
Aphanoconia (figs. 62 to 65) could have had any value in the 
difierentiation of these species by natural selection. 
Asa result of my somewhat elaborately minute studies, I am 
driven, and, I confess, somewhat unwillingly driven, to the con- 
clusion arrived at by a number of naturalists, that natural 
selection is efficient in preserving chaiucters of physiological 
importance, but inefiiective in producing new species by adding 
together numerous minute successive variations. The only 
conclusion justified by the facts seems to me to be that the 
characters on which systematists rightly rely are of the natvire 
of deviations or mutations, of no consequence to the well-being 
of the animals in which they appear, but inheritable, and there- 
fore perpetuated under favourable circumstances by segregate 
breeding. The Helicinidpe, inhabiting narrow areas, and often 
segregated in remote islands, afford particularly favourable oppor- 
tunities for segregate breeding. 
As to how far these small deviations of functionally iinimportant 
structures may be due to the influence of external conditions I 
do not venture to ofier an opinion, but the following fact is 
suggestive. Among the shells in the tube containing several 
specimens of Aphanoconia mergidensis was a, specimen which 
in size, shape, coloration, and marking so exactly resembled the 
others that I took it for a Helicinid (as the collector must also 
have taken it) and decalcihed it with a view to anatomical 
investigation. It proved to be a, Helicid, of what genus and 
species I cannot say, as I had destroyed the shell and could not 
find another specimen. 
Among the collection of Helicinid^e made in the Andaman 
Islands and presented to the British Museum of Natural History 
by Mr. G. Rogers was a tube containing half a dozen specimens 
which differ recognizably in the characters of the shell and 
operculum from Aphanoconia andamanica Benson, but ai'e clearly 
closely I'elated to that species. I have not been able to refer 
them to any named species, and as the radular characters show 
it to be distinct from andamanica, I describe it as a new species, 
as follows : — 
Aphanoconia rogersii, sp. n. (PI. XLII. figs. 65-69.) 
Shell oblately spheroidal, the surface marked with closely set 
I'adial growth-lines ; colour light orange-yellow marked with more 
or less distinct reddish-brown radial bands ; spire of 4| whorls, 
increasing regulai-ly and somewhat rapidly in size, the last whorl 
obtusely keeled, the keel produced into a, prominent angular 
802 
PROP. G. C. BOURNE ON THE 
projection at the peristome. Aperture semilunar, very oblique, 
the outer margin thickened and expanded. Basal callus not 
very thick, hardly differing in colour from the rest of the shell, 
of rather small extent, its limits clearly defined above, as well as 
below. The whole shell deej^er in proportion to its breadth than 
in A . andamanica and the sjoire more prominent. 
Operculum yellowish white in colour, the calcareous plate 
rather thin, the sigmoid curve pronounced, the upper angle 
produced. 
Radula with small diamond-shaped median tooth ; the first 
admedian tooth more than twice as long as broad, the anterior 
edge incurved and bearing four denticulations ; second and third 
admedian teeth each with four denticulations ; the lateral teeth 
normal, the stalk rather long, the articular excavation deep, the 
aliform process bearing seven round denticulations. 
Closely as the shell of this species resembles that of A. anda- 
mauica, a glance at the drawings of the radulpe of the two species 
(figs. 63 & 65) shows that they are distinct. 
I must express my obligations to Miss Margaret Poole, both 
for helping me in the determination of the different species of 
Aphanoconia and for making the drawings of shells and radulse 
for figs. 62 to 68. 
As I have discussed and offered an explanation of the geo- 
graphical distribution of the Helinicidte without either adopting 
or ci-iticizing the theories advanced by Dr. Simroth (7 and 8) on 
this subject, I must, in conclusion, make some reply to the friendly 
criticisms that he has published on my paper on the Neritidfe. 
I do not propose, in this place, to discuss the physiological 
interpretation that he has given of the different arrangements of 
the female ducts in the Neritidfe. For one thing, I have 
obtained some new material and hope soon to publish further 
observatioiis throwing fresh light upon the problems to which 
he refers : for another, I am inclined to accept much of what he 
writes on that part of the subject. 
. But with regard to the ancestry of the Neritidpe, and with them 
the Helicinidfe, which Di'. Simroth would derive from a pulmonate 
stock, and with regard to the homologies that he wishes to establish 
between the generative ducts of Neritidfe and Pulmonata, I am 
unable to accept any of his conclusions. To do so would be 
to throw the whole fabric of morphological reasoning to the 
ground. Dr. Simroth's views on homologies are largely influenced 
by a theory of secular changes in the sea-level produced by a 
swinging or " pendulating " movement of the earth about an axis 
which corresponds with the longest diameter of the earth and has 
its poles in Sumatra and Ecuador. It is not my present intention 
to discuss the difficult astronomical and geological problems in- 
volved in the " Pendulation theory," and, indeed, I am sure that T 
am incompetent to discuss them. The theory may be well founded 
or it may not : I do not offer an opinion ; but be it right or 
MORPHOLOGY OF THE HELICINID^E. 803 
wrong, I fail to see that the conclusions deduced from it by Dr. 
Simroth are necessary. I will explain as briefly as possible why. 
Unless I misunderstand him grievously, and if I do I beg his 
pardon, one of Dr. Simroth's chief conclusions is that, contrary to 
the generally accepted doctrine, marine and freshwater animals in 
general, the marine prosobi-anch Gastropods in particular, are 
evolved from terrestiial forms which have been forced by the 
above-mentioned secular inundations to adapt themselves to new 
conditions of life and make their habitat in another medium. As 
the pendulation theory applies to all geological time, if the pre- 
cursors of marine Gastropods were terresti"ial in habit, we should 
find evidence of this in geological deposits. The earliest-known 
Gastropods, from the Cambrian to the Devonian, would bear 
evidence of their terrestrial life, those found in later deposits 
would indicate, in some periods at least, the change from a ter- 
restrial to a marine existence. But, in point of fact, the geological 
evidence points decisively the other way. In Cambrian, Ordoviciaii, 
Silurian, and Devonian deposits we get Gastropods belonging 
almost exclusively to the Streptoneurous Aspiclobranchia and 
Pectinibranchia. There are, it is true, the pteropod-like shells of 
the Conularida which, if they are really remains of Pteropods, 
would demonstrate the great antiquity of highly specialized forms 
of Euthyneura. But the true systematic position of the Cornu- 
larida is at the best doubtful, and it has been urged with much 
reason and on high authority that the resemblance between the 
shells of these archaic forms and the more modern Pteropoda is 
due to parallelism. As so much doubt prevails as to their atSnities, 
the Cornularida cannot be bi-ought into the argument. The 
Aspidobranchiate and Pectinibranchia te Gastropods from these 
earlier Palaeozoic deposits are without doubt marine forms. They 
subsisted, without a,ny important changes, through the four above- 
mentioned geological epochs, and one genus, Pleibrotomaria, has 
survived to the present day. We know the habits and the 
anatomy of Pleurotomarla, and they support in a most remarkable 
manner the conclusions derived from an extensive knowledge of 
gastropod morphology. On the other hand, with the exception of 
Hercynella from the Devonian, undoubted Euthyneura first make 
their appearance in the Carboniferous, They belong to the 
Actfeonidae and Pnlmonata Stylommatophora. The first-named 
family is marine, and anatomically displays so many strepto- 
neurous characters that it might almost be included in the 
Aspidobranchia. Of the Stjdommatophora we get forms like 
Dendropu'pa and Pyramidula, unquestionably terrestrial species, 
and, according to views generally accepted, highly modified and 
therefore indicative of a line of lost ancestry probably allied to the 
contemporary Actteonidse. But these pulmonate forms are few 
and of rare occurrence in the Cai-boniferous, a period in which 
the conditions for the preservation of terrestrial and freshwater 
forms were pai'ticularly favourable. Had numerous Pulmonates 
existed at that time their remains must have been mure abundantly 
8()4 PROF. G. C. BOURNE ON THE 
preserved. Terrestrial pulmoiiates aj-e still scanty in the Permian 
and Trias, and only begin to show a considerable increase in the 
Jurassic and Ci'etaceous. I need not labour the point further. 
Clearly, palteontological evidence does not favour Dr. Sim roth's 
theory of the orgin of marine from terrestiial Gastropoda. 
But let us suppose that palteontological evidence may be ignored 
on account of the imperfection of the geological record, and tha.t 
the Pendulation theory is so well supported by other evidence as 
to compel us to give credence to Dr. Simroth's doctrines as to the 
origin of marine from terrestrial Gastropods. The Helicinidre 
are terrestrial and pulmonate. I have shown, and in so doing- 
have only corroborated the opinion of all other observei'S, that 
they are Neritoid in almost every feature of their anatomy. If 
the marine and iluviatile Neritids were to be derived from a ter- 
restrial and pulmonate form, one would suppose that that form 
must have been Helicinid in character, for the affinities between 
the two groups are so very obvious. But Dr. Simroth does not 
discuss this possibility. Making refei'ence to Ostracolethe^ 
Hycdimax, Limax, and Arion, all highly specialized recent 
Pulmonates, he boldly derives the Neritida^ from the Stylomma- 
tophora, relying largely upon the supposed homology of their 
generative ducts. This homology I do not admit : a resemblance 
there is, but not a close one, and, even if it were closer than it 
actually is, I should place very little reliance on the anatomy of 
the generative ducts as indicative of relationship between groups 
differing widely in all other respects. In the different phyla of 
invertebrated animals the generative ducts are notoriously variable 
in character. In the Platyhelmia., for example, their variety is 
bewildering. Within the phylum Mollusca there ai'e many in- 
stances of variability and also of deviations which must have been 
independently acquired but are in the same dii-ection, as, for 
instance, in the Doi-idomorpha and Elysiomorpha,. The re- 
semblances, such as they are, between the generative ducts of the 
monoecious Pulmonata and the direcious Neritidfe are just what 
one might expect to find in animals in which a common plan of 
organization, to wit a gastropod organization, is modified in 
accordance with similar physiological requirements. The differ- 
ences are of amply sufficient niagnitude to betray a difference of 
origin. In other words, the complex gonaducts of Neritida^ and 
Pulmonata are independently acquired structures, and such 
resemblances as they display ai'e due to pai'allelism. 
I have already referred to the anatomy of the Pleurotomariidas, 
a family which existed in the Cambrian and survives to the present 
day. Thanks to Bouvier and M. F. Woodward, we are well 
acquainted with the anatomy of Pleurotomaria, which affords a 
striking confirmation of the reliability of sound morphological 
reasoning. Before Pleurotomaria had been studied, comparative 
anatomists, as the result of extensive investigations of gastropod 
structure, had come to an agreement concerning numerous marks 
of primitive organization in the gioup. When this survivor from 
MORPHOLOGY OF THE HELlCINIDiE, 
805 
the Palfeozoic age came to be examined, all these marks were 
found, some of them in a more pronounced degree than in any 
other known Gastropod, and in no system of organs were these 
marks more conspicuous than in the nervous system, the im- 
portance of which Dr. Simroth seeks to minimize. Among these 
marks may be enumerated— a cerebral commissure situated far 
forward on the pharyngeal bulb ; a distinct labial commissure ; 
elongated and scalariform pedal nerve-centres ; a long crossed 
visceral commissure; two auricles to the heart: the ventricle 
lapped round the rectum; a rhipidoglossate dentition. Other 
characters might be enumerated, but these suffice for the present 
purpose. All these characters are absent in the Pulmonata : all 
of them are present in the Neritidte. Moreover, by discovering 
the oviduco-coelomic funnel, I was able to demonstrate, beyond all 
reasonable doubt, the homology of a part of the gonaducts tothe 
right kidney of Pleurotomao-ia and other rhipidoglossate Aspido- 
branchs, a homology which Thiele had already asserted on other 
grounds. Now it is quite clear that, if structural resemblance is 
of any value as a guide to affinity, we have a choice between two 
alternatives. Either the Neiitidse, to which Ave must add the 
Helicinidfe, are descended from Aspidobranch ancestors, which 
they resemble in all the points enumerated above, and have in- 
dependently acquired genital ducts superficially similar to those 
of Pulmonata ; or, as Dr. Simroth will have it, they have descended 
from stylommatophorous Pulmonata, have preserved the characters 
of the genital ducts of the latter group, but have independently 
acquired all the other characters enumerated above, characters 
possessed by no Pulmonate, but invariably present in those 
Aspidobranchs from which, on Dr. Simroth's showing, the 
Neritidaj are not descended. I am not quite sure whether he 
would go so far as to assert that the remaining Aspidobranchs 
possess those characters because they are descended from the 
Neritida;. To make such an assertion would, indeed, be flying in 
the face of all reasoned opinion on this subject, and would amount 
to a declaration tliat the geologically more recent Pulmonates are 
the parents of their predecessors of Cambrian age ! 
I submit the alternative to the judgment of my readers, and in 
doing so beg leave to entei' a protest against the growing tendency 
to throw over long-established and carefully reasoned conclusions 
founded upon morphological evidence, because of their uncon- 
formity with some new and as yet insufficiently tested hypothesis, 
or because they do not help in the solution of certain limited 
problems. I was quite aware, when I discussed the subject, that 
the geographical distribution of the Neritidt\3 was a puzzle, and 
that'l had failed to find a solution to it. The distribution of the 
Helicinidre is scarcely less puzzling and awaits a final solution. 
But with all respect 'for Dr. Simroth's authority aiid deserved 
reputation as a zoologist, I submit that the solution that he offers 
is improbable, raises a crop of other puzzles, and throws 
morphology into confusion. 
806 
PROF. G. C. BOURNE ON THE 
List of Literature referred to. 
(1) Amaudrut, a. — La pai-tie anterieure du tube digestif et la 
torsion chez les Mollusques gasteropodes. Ann. des Sci. 
Nat. (8) vii. 1898, p. 1. 
(2) Bourne, G. 0. — "Contributions to tiie Morphology of the 
Group Neritacea of Aspidobranch Gastropods. — Part I. 
The Neritidfe." Proc. Zool. Soc. Lond., 1908. 
(3) BouviEE, E. L. — ■'' Systeme nerveux, Morphologie generale 
et Classification des Gasteropodes Prosobranches." Ann. 
des Sci. Nat. (7) iii., 1887. 
(4) IsBNKRAHE, C. — " Anatomie von Helicina titanica." Arch. 
f. Naturgeschichte, xxxiii., 1867, p. 50. 
(5) Jhering, H. von. — Yergleichende Anatomie des Nerven- 
systems und Phylogenie der Mollusken. Leipzig, 1877. 
(6) KoBELT, "W. — Studien zur Zoogeographie. Wiesbaden, 1897. 
(7) SiMROTH, H. — " Neuere Arbeiten liber die Morphologie und 
Biologie der Gastropoden." Zool. Zentralblatt, Bd. xvi., 
1909. 
(8) SiMROTH, H. — "The Anatomy of the Neritidse." Proc. 
Malacol. Soc. Lond., ix. 1910, p. 27. 
(9) Thiele, J. — " Die systematische Stellung der Solenogastren 
und die Phylogenie der Mollusken." Zeitschr. f. wiss. 
Zool., Ixxii. 1902, p. 249. 
(10) Thiele, J. — " Ober die Anatomie von Hyclrocena cattaroensis 
Pf. Abh. d. Senckenbergischen Naturf. Gesell., xxxii., 
1910. 
(11) Troschel. — Das Gebiss der Schnecken. Berlin, 1856-1863, 
Bd. i. pp. 75-85. 
(12) Wagner, A. J. — " Helicinenstudien." Denkschr. d. kais. 
Akad. d. Wissenschaften, Wien, Bd. Ixxvii., 1905, and 
Ixxviii., 1906. 
(A complete list of the literature of the Neritoidea is given in 
my previous paper [2]). 
EXPLANATION OF THE PLATES. 
Plates XXX.-XLII. 
Lettering in all the figures. 
an. Anus. 
ao. Aorta. 
ap. mg. Aperture of liypobranchial 
gland. 
Au. Auricle. 
hue. Buccal cavitj'. 
ccB. Cajcum of ootype. 
cl. Cloaca, 
c. m. I. Left columellar muscle. 
c. m. r. Right columellar muscle. 
com. hucc. Buccal commissure. 
com. cer. Cerebral commissure. 
com., lah. Labial comiuissure. 
com. pel. Pedal commissure. 
com. pi. Pleural commissure. 
con.ped. Cerebro-pedal connective. 
con.pl. Cerebro-pleural connective. 
c. ph. Lateral pharyngeal cartilage. 
div. Diverticulum of male gona- 
duct. 
J5?. Eye. 
F. Foot. 
g. hucc. Buccal ganglion. 
g. cer. Cerebral ganglion. 
Gd. Gonaduct. 
gl. pd. Pedal gland. 
gl. r. Glandular ridge on floor of 
the oesophagus. 
g. pi. Pleural ganglion. 
Int. Intestine. 
MORPHOLOGY OF THE HELICINID^. 
807 
Li. Liver. 
li. d. Liver-ducts. 
M. Mantle. 
M. c. Mantle-cavity. 
m. g. Hypobranchial gland. 
n. em. I. Left columellar nerve. 
n. cm. r. Right columellar nerve. 
n. gen. Genital nerve. 
n. gl. p. Nerve to pedal gland. 
n. Ipb. Labio-proboscidean nerves. 
n. oc. Ocular nerve. 
n. op. I. Left opercular nerve. 
n. op. r. Right opercular nerve. 
n. of. Otocyst nerve. 
n. pal.-c.l. Left pallio-columellar nerve. 
n. pal.-c.r. Rightpallio-columellar nerve. 
ti.pal.l. Left pallial nerve. 
n. pal.r. Right pallial nerve. 
H.par.l. Left parietal nerve. 
n. par.r. Right parietal nerve. 
n. sb.i. Subintestinal nerve. 
n. ten. Tentacular nerve. 
od. Oviduct. 
od^. Descending limb of V-shaped 
portion of oviduct. 
od'^. Ascending limb of V-shaped 
portion of oviduct. 
od. c. a. Anterior odontophoral carti- 
lage. 
od. c. p. Posterior odontophoral carti- 
lage. 
OS. (Esophagus. 
ce. p. Esophageal pouch. 
o. OB. p. Opening of oesophageal pouch 
into oesophagus. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 17, 
Leftside view of Alcadia palliata. The mantle has been cut through close 
to the left columellar muscle and turned back to expose the interior of the 
mantle-cavitj', the pericardium has also been opened. 
Dorsal view of the buccal cavity, pharj'nx, and anterior part of the 
oesophagus of Alcadia palliata : the buccal cavity, pharynx, and part of 
the cBsophagus have been laid open ; gl.r., glandular ridge on the floor 
of the oesophagus. 
A dissection of the oesophagus and pharynx oi Alcadia palliata, seen from 
the left side. 
A horizontal section through the pharynx and buccal cavity of Alcadia 
hollandi. 
The odontophoral cartilages oi Alcadia palliata, viewed from below. 
The odontophoral cartilages of JSutrochatella pulcJiella, viewed from above. 
A dissection of the stomach of Alcadia palliata, viewed from the ventral 
side. 
A portion of the epithelium of the stomach of Alcadia hollandi, showing 
glandular and ciliated cells. X about 960. 
Part of a section through the prominent ridge in the stomach of Alcadia 
hollandi, X about 600 ; cu., the thick cuticle covering the ridge. 
The alimentary tract of Alcadia palliata, showing the arrangement of the 
intestinal coils. 
Alimentary tract of Alcadia hollandi. 
Alimentary tract of Falmohelicina idee. 
Alimentary tract of Orobophana ponsonbyi. 
Alimentary tract of Lucidella aureola. 
Alimentary tract of JSutrochatella pulchella. 
A hoi'izontal section through the upper part of the visceral mass of 
Alcadia hollandi. Figs. 17 to 22 are drawn from the same series of 
sections. 
A section somewhat lower down, showing the origin of the ureter, Ur., 
from the kidney. 
808 ON THE MORPHOLOGY OF THE HELICINIDJE. 
Fig. 18. A section still more ventral than the above, showing the deepest part of the 
pericardium and its relation to the kidney. 
¥ig. 19. A more ventral section passing through the reno-pericardial canal, 
7'.p.C. 
Pig. 20. A similar section passing through the ventral part of the visceral mass. 
Fig. 21. Part of a section slightly ventral to that drawn in fig. 19, showing the 
uropore, Ur.p., opening into the mantle-cavity. 
Fig. 22. A section through the reno-pericardial canal. Magnified about 600. 
Pig. 23. Part of a section passing through the uropore of Lucidella aureola and 
showing the character of the renal epithelium. X 960. 
Pig. 24. A diagram reconstructed from the series of sections drawn in figs. 16 to 20, 
showing the relations of the kidney, ureter, stomach, pericardium, and 
mantle-cavity. 
Pig. 25. The genital ducts of Alcadia hollandi $ . The lower half of the figure is 
drawn as it appears when viewed by transmitted light, the upper part as 
seen by reflected light. In this and in figs. 26-29, 40, and 41, the 
gonaducts are represented as seen from the ventral side, after the wall of 
the mantle-cavitjr has been cut throvigh by a dorsal incision and the 
rectum and gonaducts turned over to the right side of the animal. 
Fig. 26. The gemt-A\ dwciii oi Eutrochatella jjulchella $. 
Fig. 27. The genital ducts of Aplianoconia mergiiiensis $ . 
Pig. 28. The genital ducts of Palaohelicina idee. '^ . ' 
Pig. 29. The genital ducts of Oro6o_pAfl'«a^o»so«6r/» $. 
Fig. 30. A longitudinal section through the genital ducts of Alcadia hollandi '^ , 
passing through the aperture of the hypobranchial gland. 
Fig. 31. A longitudinal section from the same series, showing the aperture of the 
vaginal duct. 
Ifig. 32. Another section from the same series, showing the origin of the oviduct 
from the ovarian chamber. 
Fig. 33. Another section from the same series showing the connection of the vagina 
with the vaginal sac and ootype. 
Fig. 34. Another section from the same series showing the opening of the oviduct, od., 
into the descending limb of the V-shaped tube, od.' 
Fig. 35. Another section from the same series showing the receptaculum seminis 
opening into the ascending limb of the V-shaped tube. 
Fig. 36. Glandular epithelium from the wall of the ootype of Alcadia Jiollandi. 
Fig. 37. Ciliated epithelium and spermatozoa from the receptaculum seminis of 
Alcadia hollandi. 
Fig. 38. A section through the oviduct of Alcadia hollandi. Highly magnified. 
Fig. 39. An epithelial ridge from the bilobed caecum of the ootype of Orobophana 
/onsonbt/ir. 
view of the genital ducts o{ Alcadia hollandi ,$ . 
Fig. 41. A similar view of the genital ducts of Aphanoconia gouldiana $ . 
Fig. 42. A drawing made from a combination of several serial longitudinal sections 
through the genital ducts of Etitrochatella pulchella $ , showing the 
narrow diverticulum, k.r., which may possibly represent the vagina of the 
female and therefore be the homologue of the right kidney-sac. 
Fig. 43. A dissection showing the pedal, pleural, and visceral nerve-centres in 
Alcadia palliata, with the principal nerves issuing from them. The 
cerebral ganglia have been removed. The dissection is made from the 
dorsal surface ; the foot, as is usual m contracted specimens, is turned 
forward and lies in front of the head with the sole uppermost; the vi'alls 
of the head and the mantle have been cut away, and the visceral mass has 
been dissected as far as is necessary to show the course of the subintestinal 
nerve and its branches. 
Fig. 44. The nerve-centres and principal nerve-trunks of Alcadia hollandi, viewed 
from the right and above. The drawing was made with the camera 
lucida, after removal of the nerve-centres from the body. 
Figs. 46-52. A series of transverse sections through the pleuro-pedal nerve-centres of 
Alcadia hollandi, showing the principal tracts of nerve-fibres in the fused 
pedal, pleural, and subintestinal ganglia. For a full description of these 
figures, see the text, p. 789. The position of the pedal gland is indicated 
in fig. 45. 
Fig. 53. The left cerebral ganglion of Palceohelicina idee, viewed from the inner 
surface. The ganglion is stained with Mayer's hfemalum and drawn by 
transmitted light ; 1, 2, 3, 4, the four labio-proboscidean nerves. 
Fig. 54. A similar preparation of the left cerebral ganglion of Alcadia palliata. 
ON TUE PALATABILITY OF SOME BRITISH INSECTS. 809 
Fig. 55. A drawing of a section showing the position, structure, and nerve-supply of 
the opercular organ of EutrochateUa jjulclieUa. 
Fig. 56. A portion of the epithelium of the hypobranchial gland of Alcadia 
hollandi. Highly' magnified. 
Fig. 57. A left lateral tooth from the radula of EutrocJiatella 'pulchella. Highly 
magnified. 
Fig. 58. Radular teeth of AJcailia Inilhaiili, highly magnified : a, median ; 6, c, d, 
first, second, and third admedians of the left side ; f, one of the marginals 
or uncini ; e, a lateral tooth of the right side showing the stalk, stk., the 
aliform internal plate, al.p., the articular excavation, ari., and the 
process, ext.jj. 
Fig. 59. Three rows of teeth from the radula of LiicideUa aureola. In this and 
the following figures only the pro.ximal members of the marginals are 
indicated. 
Fig. 60. Two rows of teeth from the radula of PaJceohelicina idte. 
Fig. 61. Two rows of teeth from the radula of Orohophana pachystoma ponsonhyi. 
Fig. 62. Two rows of teeth from the radula of Aphanoconia ffouldiana. 
Fig. 63. Two rows of teeth from the radula oi Aphanoconia andamanica . 
Fig. 64. Two rows of teeth from the radula of Aphanoconia merguiensis. 
Fig. 65. Two rows of teeth from the radula oi Aphanoconia rogersii. 
Fig. 66. Shell of Aphanoconia rogersii. 
Fig. 67. Shell of the same species, showing the aperture. 
Fig. 68. Shell of the same species, viewed from above. 
Fig. 69. Operculum of Aphanoconia rogersii, viewed from the inner or ventral side. 
3G. On the Palatability of some British Insects, with Note.s 
on the Significance of Mimetic Resemblances. By 
R. I. PococK, F.R.S., F.L.S., F.Z.S., Superintendent 
of the Society's Grardens and Curator of Mammals. 
With Notes upon the Experiments. By P^f. E. B. 
PouLTON, F.R.S., F.Z.S. 
[Received and Read May 9, 1911.] 
Introduction. 
At the request of Prof. E. B. Poulton, F.R.S., I undertook, in 
the summer of 1909 and again in that of 1910*, to make a series 
of experiments in the Zoological Gardens to test the palatability 
of various species of British Insects. Much of the material was 
sent to me by Dr. G. B. Longstaft' from Morthoe in Devonshire. 
Some I received from Prof. Poulton himself or from friends of 
his. A few species I added on my own account ; notably the 
stick insects and the ants, of which we had an abundant supply 
in the Insect House in the Gardens. Those that I supplied 
I identified myself. The rest were in all cases named by the 
senders. To the insects Dr. Long.staif added a number of slugs, 
which were identified, I understand, by Mrs. Longstaff. 
Since the majority of the experiments were made with English 
Insects, it is regrettable that English, or at all events Palsearctic 
birds, were, for the most part, unavailable for the tests. There 
were two reasons for this. In the first place, Palsearctic insecti- 
vorous birds were not sti'ougl)' repi-esented in the Society's 
* Records of a few experiments made in 1911 have been incorporated in the text,