494 Mr. C. T. Regan — A Revision 
red (orange-ferruginous) ; second segment entirely clear red ; 
third red, with a large, siiflFused, dusky, dorsal shade ; 
remaining segments black ; third and following segments 
with apical bands of white tomentum, such bands also at 
sides of second; hair at apex of abdomen white; fourth 
ventral with a prominent median apical lobe. 
Hub. Nasik, India [E. Comber). BritiNh ]\Iusenra. 
Runs in Bingham's table to N. pilipes, Smith, but the 
colour of the pubescence and wings is so different that it 
cannot be the male of that species. There is a striking 
superficial resemblance to N. phenacura, Ckll., also found at 
Nasik, but the sculpture of the thorax is entirely different, 
especially that of the metathoracic area. 
LXI. — A Revision of the Pceci/iid Fishes of the Genera 
Rivulus, Pterolebias, and Cvnolebias. Bv 0. Tate Regan, 
M.A. 
(Publislied by permission of the Trustees of the British Museum.) 
The three closely related genera here dealt with are the 
neotropical Fundulinse *. In them the snout is short, the 
margin of the eyes is not free, and the gill-membi'anes are 
separate. The mouth is ratiicr wide and transverse, with 
the prremaxillaries protractile, but not produced, and the 
lower jaw^ prominent and very oblique ; the teeth are sub- 
conical, in bands, with an outer series of enlarged and 
spaced teetii, more or less canine-like, a lateral pair in the 
lower jaw being usually the strongest. The membrane 
connecting the praemaxiliary with the lower jaw folds when 
the mouth is closed so as to fit into the right angle formed 
bv the very narrow vertical preeorbital and the horizontal 
nasal. The pectorals are placed low and the pelvics are not 
far in advance of the anal. 
I give a list of the specimens in the British Museum 
collection, including the types of four species now described 
as new. Two of these, Rivulus strigatus from the Amazon 
and Cynolebias nigripinnis from the La Plata, have been 
* Except that a few species of the nearctic genus Fwidulus occur in 
Central America. 
I take this opportunity of proposing the new generic name Peta- 
lurichihys, to replace Petalosoma, Regan, 1908, as Mr. C. O. Waterhouse 
has kindly called my atteution to tlie fact that this is preoccupied in 
Coleoptera (Lewis, Ann. & Mag. Nat. Hist. (7) xii. 1903, p. 418;. There 
are two species of this neotropical Pceciliid genus, viz. Petalurichthjs 
cidtrutus, Kegan, 1908, and P. umazonmn, Regan, 1911. 
of Puiciliid Fishes. 495 
presented by Herv J. Paul Arnold, one, Rivulus brevis from 
Colombia, by Dr. W. WolterstorfF, and the fourth, Cyno- 
lebias melanotcenia from Parauagua, by Herr A. Rachow. 
HlVULUS. 
Rivulus, Poey, Mem. Cuba, ii. 1861, p. ;507. 
Cynodonichthys, Meek, Publ. Columbiau Mus. Zool. v. 1904, p. 101. 
In. this genus the dorsal is shorter and further back than 
the anal. D. 6-11. A. 8-17. The pelvic Hus are sniall. In 
the typical species the head is depressed and the body i.s 
subcyliudrical anteriorly, moderately compressed posteriorly ; 
sometimes (e. g. R. brevis) the fish is compressed through- 
out. 
Twenty-two species from Central and South America, 
ranging from Cuba and Southern Mexico to the La Plata. 
Synopsis of the Species. 
I. 45 to 52 scales iu a longitudinal series. 
D. 10-11. A 14-16. Dorsal origin twice as disr 
tant from eye as from base ot caudal 1. jiertianus. 
D. 9. A. 16-17. Dorsal origin twice or more 
than twice as distant from head as from base 
of caudal 2. hohni<B. 
D. 8-9. A. 11-12 3. qcellatus. 
II. 36 to 42 scales in a longitudinal series. 
A. Anal ending below anterior part or middle of dorsal. 
1. D. 6-8. 
A. 11-13. Dorsal origin more than twice as disr 
tant from bead as from base of caudal. 
Caudal with ocellus in $ , without pale or 
dark lower edge in J 4. urophthalmus. 
A. 12-15. Dorsal origin about twice as distant 
from head as from base of caudal. Caudal 
without ocellus in ^ > with dark lower edge 
in c? 5. filegans. 
A. 11-12. Dorsal origin less than twice as dis- 
tant from bead as from base of caudal. 
Caudal with ocellus in g , with pale lower 
edge and dark intramargiual stripe in cJ . . 0. godmani. 
A. 11-12. Dorsal orijiin more than twice as dis- 
tant from head as from base of caudal. 
Caudal as in R. (jodmaiii 7. tenuis. 
2. D. 9-10. A. 12-14 8. fabeUicauda. 
B. Anal ending below posterior part of dorsal. 
D. 10-11. A. 13 9. cylindraceus. 
D. 9. A. 14. Dorsal origin 2^ bead-lengths 
behind head 10. micropus. 
D. 8-10. A. 15-17. Dorsal origin less than 
2 head-lengths behind head 11. hartii. 
34* 
496 Mr. C. T. Regan— A Bevision 
III, 28 to 35 scales in a longitudinal series. 
A. D. 0. 29 to 31 scales in a longitudinal series. 
A. 10-11, ending below first ray of dorsal, 
which is twice as distant from base of 
. pectoral as from base of caudal 12. ornatus. 
A. 9-10 ; dorsal origin 3 times as distant from 
occiput as from base of caudal 13. atratus. 
A. 8 ; dorsal origin above middle of anal, 3 times 
as distant from middle of eye as from base of 
caudal 14. obscurus. 
B. D.7-9. A. 10-13, ending below middle of dorsal. 32 1 
scales in a longitudinal series. 
Dorsal origin twice as distant from bead as from 
base of caudal 15. strigatus. 
Dorsal origin twice as distant from some part of 
eye as from base of caudal 16. (jeatji. 
Dorsal origin three times as distant from eye as 
from base of caudal . 17. pmictatusf. 
C. D. 8-10. A. 11-14, ending below posterior part of dorsal. 
a. A. 11 to 12. 31-33 scales in a longitudinal series. 
Dorsal origin twice as distant from head as from 
base of caudal 18. isthmensis. 
Dorsal origin equidistant from middle of pectoral 
and base of caudal ; head 3^ in length offish ; 
pectoral nearly reaching pelvics ]9. brasi/ie7isif<. 
Dorsal origin equidistant from middle of pectoral 
and base of caudal ; head 4 in length of fish ; 
pectoral not nearly reaching pelvics 20. hreviceps. 
b. A. 14. 
34 scales in a longitudinal series 21. bakanii. 
30 scales in a longitudinal series 22. brevis. 
1. Rivulus peruanus. 
Haplochihis peruanus, Regan, Ann. Mag. Nat. Hist. (7) xii. 1903, 
p. G26. 
Depth of body about 5 in length, length of head about 4. 
Head broader than deep. Diameter of eye 3^ in the length 
of head. 45 to 47 scales in a longitudinal series. Dorsal 
10-11 ; origin above middle of anal, twice as distant from 
eye as from base of caudal. Anal 14-16, ending below last 
2 or 3 rays of dorsal. Pectoral f or f length of head, not 
reaching pelvics, which do not or barely reach the vent. 
Brownish, with darker longitudinal stripes along the series 
of scales and small dark spots on the vertical fins. 
Peru. 
1-2 (typ^s)- ■^S mm. Perim, Peru, 800 metres. Simons. 
of Poeciliid Fishes. 497 
2. Rivulus holmice. 
Hivulus kolmifB, Eigenm. Ann. Carnegie JMus. vi. 1909, pp. 49, 50 ; 
Mem. Carnegie Mus. v. 1912, pp. 452, 458, pi. Ixiii. tigs. 2, 3. 
Hivulus xoaimacui, Eigenm. /. c. & t. c. pp. 452, 454, pi. Ixiii. figs, 4, 5. 
Depth of body about 5 ia the length, length of head 4 to 
4f . Head broader than deep. Diameter of eye 3^ to 4 in 
the length of head. 46 to 50 * scales in a longitudinal 
series Dorsal 9 ; origin above posterior part of anal, at 
least twice as distant from head as from base of caudal. 
Anal 16-17, ending below middle or posterior part of dorsal. 
Pectoral | length of head, not extending to pelvics, which 
just reach vent. In spirit brownish, with darker spots 
which may become confluent to form longitudinal stripes, of 
which 3 on the tail are most prominent ; vertical fins with 
series of small spots ; caudal ocellus sometimes present. In 
life the back olive, sides olive or blue, belly white, yellow, or 
orange, spots or stripes red, brown, or purplish. 
British Guiana. 
1-2 (co-types). £0-60 mm. Holmia. Eigenmaun. 
3-4 (co-types of -R. waimacui). Shrimp Creek. „ 
3. Rivulus ocellatus. 
Hivulus ocellatus, Hensel, Arch. f. Nat. xxxiv. 1868, p, 365, 
Depth of body 4^ to 5 in the length, length of head 3f 
to 4. Head broader than deep. Diameter of eye 3^ to 4 
in the length of head. 47 to oO scales in a longitudinal 
series. Dorsal 8-9 ; origin above posterior part of anal, 
twice as distant from base of pectoral as from base of caudal. 
Anal 11-12, ending below anterior part of dorsal. Pectoral 
f or I the length of head, not extending to pelvics, which 
reach the vent. A dark spot (ocellated in $ ) on upper part 
of base of caudal, another above the pectoral ; vertical fins 
more or less distinctly spotted ; male with irregular dark 
cross- bands on body and with a blackish margin and pale 
intramarginal baud to vertical fins. 
Rio Janeiro ; Santos. 
1. 60 mm. Santos Arnold. 
2-3. 40-45 mm, „ Bartsch. 
Dr. Pappenheira has very kindly informed me that the 
type has 48 to 50 scales in a longitudinal series, not 39 as 
stated in the original description. 
* Eigeumann counts 43 scales in holmice, 46 to 52 in tmimacid, but in 
co-types of the former 1 count 46 and 47, of the latter 47 and 50. 
498 Mr. C. T. Regan — A Revision 
4. Rivuhis urophthahiiHS. 
iiivulue urophthahnus, Giinth. Cat. Fish. vi. p. 327 (1866). 
Rivulus poeyi, Steind. Sitzungsb. Akad. Wien, Ixxiv. 1877, p. 165. 
Jiivulus brasiliensis {non Val.), Garman, Mem. Mus. Comp. Zool. xix. 
• 1895, p. 135. 
Rivulus stagnaius, Eigeiim. Anu. Carnegie Mus. vi. 1909, pp. 49, 50; 
Mem. Carnegie Mus. v. 1912, pp. 453, ^54, pi. Ixiii. figs. 0, 7. 
Rivtdus laiiceokitus, Eigenm. t. c. pp. 49, 51 & t. c. pp. 453, 455, 
pi. Ixiv. fig. 1. 
Rivulus frenatus, Eigenm. I. c. & t. c. pp. 453, 455, pi. Ixiv. fig. 2. 
Depth of body 4^ to 5^ iu the length, length of head 4 
to 44. Head broader than deep. Diameter of eye 3 to 3f 
in the length of head. 37 to 42 scales in a longitudinal 
seriesi Dorsal 6-7 ; origin above last rays of anal, more 
than twice as distant from head, and 2| to 3^ as distant 
from feye as from base of caudal fin. Anal 11-13^ ending 
below anterior part or middle of dorsal. Pectoral ^ the 
length of head3 not extending to pelvics, which just reach 
the vent. Olivaceous ; each scale sometimes with a dark 
spot ; sometimes longitudinal stripes between series of scales 
on sides ; dorsal, caudal, and sometimes anal with series of 
small dark spots; caudal ocellus sometimes present ( ? ). 
Amazon ; Guiana. 
1-5 (types). 35-60 mm. Para. 
6-8. 35-45 mm. ,, Eigenm ann, 
7-9 (co-types of i2.eif/^?in<Ms). 35-38 mm. Cbristianburg. „ 
This description was written from the Para specimens and 
was fonnd to need no modification to include the co-types of 
R. stagnaius. R. lanceolatus is evidently the same species, 
the apparently different form of the caudal fin being due to 
the fact that it is less expanded. R. frenatus is said to have 
oidy 23 scales in front of the dorsal and the anal origin 
equidistant from base of caudal and prceoperculum, but from 
the figure it would seem that there are about 29 scales from 
head to origin of dorsal fin and that the anal origin is equi- 
distant from base of pectoral and base of caudal, as in small 
specimens of R. urophthahnus from Para, or in the co-types 
of R. stagnatus. 
5. Rivulus elegans. 
Rivulus eleyans, Steiud. Denkschr. Akad. Wien, xlii. 1880, p. 85, 
pi. vi. fig. 6. 
Depth of body about 6 in the length, length of head 
about 4. Head broader than deep. Diameter of eye 3 to 
3^ in the length of head. 36 to 40 scales in a longitudinal 
series. Dorsal 6-8 ; origin above posterior ^ of anal, about 
f 
of Pceciliid Fishes, -109 
twice as distant from head as from base of caudal, or 2| to 
2| as distant from eye. Anal 12-15, ending below anterior 
part or middle of dorsal. Pectoral about f the length of 
head, not extending to pelvics, which usually just reach the 
vent. Olivaceous ; often with dark longitudinal stripes 
between the series of scales ; males with 3 dark longitudinal 
stripes on back from occiput and eyes to dorsal fin, which, 
in the females, are broken up into series of spots that 
generally extend transversely, forniing a zigzag pattern ; 
vertical fins plain, the caudal and anal with lower edge 
dark {S) or dorsal and caudal with series of small 
spots ( ? ). 
Colombia. 
1-10. 25-55 mm. R. Condoto, R. San Juan, Palmer, 
S.W. Colombia. 
6. Rivulus godmani. 
Itivulus godmani, Regan, Ann. & Mag. Nat. Hist. (7) xix. 1907, p. 65, 
and Biologia Centr.-Am., Pisces, p. 82, pi. x. fig. 5. 
Depth of body 4| to 5 in the length, length of head 3|. 
Head broader than deep. Diameter of eye 3 in the length 
of head. 36 scales in a longitudinal series. Dorsal 8 ; 
origin above posterior part of anal, 21 to 2j as distant from 
eye as from base of caudal fin. Anal 11-12, ending below 
middle of dorsal. Pectoral f length of head, not extending 
to pelvics, which reach the vent. Olivaceous, marbled with 
darker ; a dark spot on each scale ; operculum blackish ; 
caudal with an ocellus ( $ ) or with a pale lower margin and 
dark intramargiual stripe {S)- 
Guatemala. 
1-2 (types). 40 mm, Guatemala. Godman. 
7. Rivulus tenuis. 
Ci/nodonichtht/s tenuis, Meek, Publ. Columbian Mus. Zool. v. 1904, 
p. 101, fig. 27. 
Hivulus tenuis, Regan, Biologia Centr.-Am., Pisces, p. 82 (1907). 
Depth of body 4| to 5 in the length, length of head 
4 to 4i. Head broader than deep. Diameter of eye 3^ to 4 
in length of head. 38 scales in a longitudinal series. 
Dorsal 7-8 ; origin 2? to 3 times as distant from eye as 
from base of caudal fin. Anal 11-12, ending below middle 
of dorsal. Pectoral f length of head, not extending to 
pelvics, which may reach vent. Olivaceous ; back and sides 
sometimes marbled ; operculum blackish ; caudal with an 
500 Mr. C. T. Regan — A R^^vision 
ocellus (?) or with rather broad pale lower edge and dark 
intramarginal stripe {^). 
Southern Mexico. 
1-2. 30-40 mm. Coaxacoalcos. Arnold. 
. 3. 40 mm. „ Bartscb. 
8. llivulus flabellicauda. 
Rivuliis fabellicamla, Eegaii, Aim. & Maj^. Nat. Hist. (7) xix. 1907, 
p. (34 ; Biologia Cenir.-Am., Pisces, p. 81, pi. x. fig. G (1907). 
Depth of body 4^ in the length, length of head 3^. Head 
broader than deep. Diameter of eye 3|^ to 4 in the length 
of head. 40 to 42 scales in a longitudinal, series. Dorsal 
9-10 ; origin above posterior part of anal, twice as distant 
from preeoperculum as from base of caudal fin. Anal 12-14, 
ending below middle of dorsal. Pectoral | the length of 
head ; pelvics just reaching vent. Brownish ; scales dark- 
edged ; vertical fins with small spots • a caudal ocellus. 
Costa Rica. 
1 (type). 70 mm. Juan Virias. Underwood. 
2. 30 mm. San Jose. Biolley. 
9. Eivulus cylindraceus. 
Rlvulus cylindrucetts, Poey, Mem. Cub. ii. 1801. p. 308 ; An. Soc. Esp. 
V. 1876, p. 140, pi. V. fig. 4, and ix. 18S0, p. 247, pi. viii. fig. 1 ; 
Giintli. Cat. Fish. vi. p. 327 (1866) ; Garman, Mem. Mus. Comp. 
Zool. xix. 1897, p. 134. 
Rivulus marmoratits, Poey, Ann. Soc. Esp. ix. 1880, p. 248. 
Depth of body about 4^ in the length, length of head S^. 
Head broader than deep. Diameter of eye 4| in length of 
head. 38 or 39 scales in a longitudinal series. Dorsal 10-11 ; 
origin over middle of anal, twice as far from occiput as from 
base of caudal. Anal 13, extending back nearly as far as 
dorsal. Olivaceous, uniform or marbled ; centres of scales 
darker ; a caudal ocellus. 
Cuba. 
Total length 45 mm. 
10. Rivulus micropus. 
Fundulus micropus, Steiud. Sitzungsb. Akad. Wien, xlviii. 1863, 
p. 184. 
Depth of body about 5 in the length, length of head about 
4^ (5| in total). Head broader than deep. Diameter 
of eye 4 in length of head. 41 scales in a longitudinal 
series. Dorsal 9 ; origin .2^ head-lengths from gill-opening. 
Anal 14, ending somewhat before the end of dorsal. 
of Pa'dliid Fishes. 501 
Pectoral as long as Lead without snout ; pelvics not nearly 
reaching anal. Brownish above, yellowish below ; vertical 
fins with series of small dark spots. 
Kio Negro. 
11. Rivulus hartii. 
Hivulus micropus (non Steind.), Giinth. Cat. Fish. Vi. p. 327 (1866) ; 
Garman, Mem. Mus. Comp. Zool. xix. 1895, p. 136. 
Hapluchiius hartii, Bouleng. Ann. Si Mag. Nat. Hist. (6) vi. 1890, 
p. 190 ; Eegan, Proc. Zool. Soc. 1906, i. p. 389, pi. xxi. fig. 2. 
Depth of body 4^ to 5^ in the length, length of head 3| 
to 4. Head broader tliau deep. Diameter of eye 3 to 4 in 
the length of head. 37 to 42 scales in a longitudinal series. 
Dorsal 8-10 ; origin above middle or posterior part of anal, 
twice as distant from some part of operculum as from base 
of caudal fin. Anal 15-17^ ending below posterior ^ of 
dorsal. Pectoral about | the length of head, not extending 
to pelvics, which reach vent or origin of anal. Olivaceous; 
sides with a red spot on each scale; vertical fins usually 
orange, with or without small dark spots : caudal ocellus 
often present. 
Venezuela and neighbouring islands. 
1-10 (types). 70 mm. Trinidad. Hart. 
11,12-15. 35-95 mm. „ Guppy. 
l(>-25. 75 mm. Granada, AVilton. 
26-27. 35 mm. Venezuela. Dyson. 
12. Rivulus ornalus. 
Rivulus ornatus, Garman, Mem. Mus. Comp. Zool. xix. 1895, p. 139. 
Form of the majority of the species. Length of head 4 
in that of the fish. Diameter of eye 4 in length of head. 
31 scales in a longitudinal series. Dorsal 6 ; origin twice 
as distant from base of pectoral as from base of caudal. 
Anal 10-11, ending below first ray of dorsal. Pectoral as 
long as head, nearly reaching pelvics, which do not reach 
anal. Puncticulations form blotches along the back, streaks 
along the sides, series of small spots on the fins, a baud on 
the lower lip, and a streak backward from below each eye; 
sometimes pale bands on the back meet dark vertical bars 
on sides. 
Amazon. 
Total length 35 mm. 
502 Mr. C. T. Regan— A Revision 
13. Rivulus atratus. 
Rivulus atratus, Garman, Mem. Mii.s. Comp. 2ool. xix. 1895, p. 140. 
Depth of the body 6 in the length, length of liead 4. 
Head broader than deep. Diameter of eye 3^ in length of 
head. 31 scales in a longitudinal series. Dorsal 6 ; origin 
3 times as distant from occiput as from base of caudal ; base 
its length further back than that of anal. Anal 9-10. 
Pectoral nearly as long as head ; pelvics very small, not 
reaching vent. Brownish ; blackish below, with three 
vertical bands ascending respectively behind the pectorals, 
between pelvics and anal, and to the base of the dorsal ; a 
dark stripe from eye round chin. 
Jutahy. 
14. Riirulus ubscurus. 
Rivulus obscurus, Garm. Mem. Mus. Comp. Zool. xix. 1895, p. 140. 
Moderately slender, with the head broader than deep. 
Diameter of eye 3 in length of head. 29 scales in a longi- 
tudinal series. Dorsal 6 ; origin above middle of anal, 3 
times as distant from middle of eye as from base of caudal. 
Anal 8, about half its base in front of dorsal. Pelvics hardly 
reaching anal. Back brownish, sometimes with darker 
blotches, among which there may be two series of pale 
blotches. 
L. Hyauuary, Amazon. 
15. Rivulus strigatus, sp. n. 
Depth of body 5 in the length, length of head 4. Head 
broader than deep. Diameter of eye 3^ in the length of 
head. 33 scales in a longitudinal series. Dorsal 8 : origin 
twice as distant from head as from base of caudal. Anal 13, 
ending below middle of dorsal. Pectoral | the length of 
head, not reaching pelvics, which extend to origin of anal. 
Olivaceous above, orange below ; dark longitudinal stripes 
along series of scales on sides; irregular spots on back; 
dorsal, caudal, and posterior part of anal barred. 
Amazon. 
1 (type). 37 mm. Amazon. Arnold. 
16. Rivulus geayi. 
Rivulus geayi, Vaill. Bull. Mus. Paris, 1899, p. 156. 
Depth of body 4^ to 5 in the length of head, length of 
I 
of Poiciliid Fishes. 503 
Head Wader than deep. Diameter of eye 4 
111 the" length of head. 33 or 34 scales in a longitudinal 
series. Dorsal 7-9 ; origin twice as distant from some part 
of eye as from base of caudal. Anal 10-12, ending below 
middle of dorsal. Pectoral | length of head, not extending 
to pel vies, which reacli origin of anal. A few dark bars or 
vertically expanded spots on the tail ; dorsal and caudal fins 
usually spotted or barred. 
Frencii Guiana. 
1-5 (co-types). 25-35 nun ; CarseTeune. Paris Mus. (Coll. Geay). 
17. Rivulus punctatus. 
JRivulus punctatus, Bouleng. Boll. Mus. Torino, x. 1895, no. 196, p. 3. 
Depth of body 4j to 4| in the length, length of head 
about 4. Head nearly as deep as broad. Diameter of eye 
about 4 in length of head. 32 to 35 scales in a longitudinal 
series. Dorsal 7-8 ; origin above posterior part of anal, 3 
times as distant from eye as from base of caudal. Anal 
12-13, ending below middle of dorsal. Pectoral | the length 
of head or a little more, sometimes almost reaching pelvics, 
which extend to the vent. A dark longitudinal band from 
chin through eye, sometimes continued to the tail ; brownish 
above, yellowish below the band ; small dark spots on sides, 
mostly forming series running obliquely downward and 
forward ; vertical fins with series of spots ; anal usually 
dark-edged. 
La Plata. 
18. Rivulus istfimcnsis. 
Rivulus isthmensis, Garman, Mem. Mus. Comp. Zool. xix. 1895, p. 140. 
Length of head 3J in length of fish. Head depressed. 
Diameter of eye 3 in length of head. 32 scales in a longi- 
tudinal series. Dorsal 9 ; origin over middle of anal, twice 
as distant from head as from base of caudal. Anal 11, last 
rav nearly as far back as that of dorsal. Olivaceous ; a dark 
blotch at base of dorsal, another on back above or in front 
of origin of anal. 
Kio San Jose, Costa Rica. 
504 Mr. C. T. Eeoan — A Revision 
19k Rivulus br 
Inndulus bradliensis, Val. in Humboldt, Observ. Zool. ii. p. 163, pi. lii. 
fig. 2 (1828) ; Cuv, & Val. Hist. Nat. Poiss. xviii. 1846, p. 200. 
Depth of body 4 in the length, length of head 3|. Diam- 
eter of eye about 3| in the length of head. 30 or 31 scales 
in a longitudinal series. Dorsal 8; ori^iin above anterior 
part of anal, equidistant from middle of pectoral and base of 
caudal. Anal 11, ending below end of dorsal. Pectoral 
almost reaching pel vies, which reach anal. Brownish ; 9 or 
10 blackish bars on lower part of body, from pelvic fin to 
caudal ; dorsal dusky. 
Brazil. 
Total length 2^ inches. 
I am indebted to Dr. Pellegrin for kindly informing me 
that he counts 30 or 31 scales in a longitudinal series in the 
types ; this is quite a dift'erent species from R. urophthalmus. 
20. Rivulus breviceps. 
Rivuhis breviveps, Eigenm. Ann. Carnegie Mus. vi. 1909, pp. 48, 49; 
Mem. Carnegie Mus. v. 1912, pp. 452, 453, pi. Ixiii. fig. 1. 
Depth of body 4^ in the length, length of head 4. Head 
broader than deep. Diameter of eye 3^ in length of head. 
33 scales in a longitudinal series. Dorsal 9-10 ; origin 
above anterior part of anal, equidistant from middle of 
pectoral and base of caudal. Anal 11-12, ending below 
posterior part of dorsal. Pectoral ^ length of head, not 
extending to pelvics, which just reach anal. Brownish; a 
few vertical bars across middle rays of caudal. 
British Guiana. 
1 (co-type). 35 mm. Shrimp Creek. Eigenmann, 
21. Rivulus balzanii. 
Haplochilus balzanii, Perugia, Ann. Mus. Genova, (2) x. 1891, p. 653. 
Depth of body 4 in the length, length of head 3. Head 
depressed. Diameter of eye 3 in length of head. 34 scales 
in a longitudinal series. Dorsal 9, originating above seventh 
ray of anal. Anal 14. Sides with 4 or 5 brownish longitu- 
dinal stripes, each covering a series of scales ; dorsal and 
anal with 3 series oE brown spots. 
Villa Maria, Matto Grosso (Rio Paraguay). 
22. Rivulus brevis, sp. n. 
Depth of body 3§ in the length, length of head 3|. Head 
of Poeciliid Fishes. 505 
a little deeper than broad. Diameter of eye 3 in the length 
of head. 30 scales in a longitudinal series. Dorsal 9 ; 
origin in advance of middle of anal, twice as distant from 
eye as from base of caudal. Anal 14, ending below last 2 or 
3 rays of dorsal. Pectoral | the length of head, extending 
beyond hase of pelvics, which extend beyond origin of anal. 
Brownish, with a darker spot on each scale of upper part of 
sides ; dorsal and anal barred ; caudal dusky. 
Colombia. 
1 (type). 45 mm. Colombia. Wolterstorff; 
Pterolebias. 
Garman, Mem. Mus. Comp. Zool. xix. 1897, p. 141. 
This genus appears to differ from Rivulus in the deep, 
strongly compressed tail, with sharp lower edge, and in the 
elongate fin-rays, the pelvics extending to the posterior end 
of the anal. 
1. Pterolebias longipinnis. 
Pterolebias longipinnis, Garman, Mem. Mus. Comp. Zool. xix. 1897, 
p. 142. 
Dorsal 9-10. Anal 19-20. 31 or 32 scales in a longitu- 
dinal series. Brownish ; fins spotted. 
Santarem. 
Total length 80 mm. 
Cynolebias. 
Steind. Sitzungsb. Akad. Wien, Ixxiv. 1876, p. 172. 
This genus differs from Rivulus in the subequal many- 
rayed dorsal and anal fins ; the species are deeper and more 
compressed than most of the Rivuli. 
Synopsis of the Species. 
I. Pectoral fin not extending beyond origin of anal, which is nearly 
below that of the dorsal, nearer to base of caudal fin than to end 
of snout. 
A. Pelvics not reaching anal. 
28 scales in a longitudinal series. D. 16-18. A. 17-20. \. melanotcenia. 
45 to 50 scales in a longitudinal series. D. 17. A. 20. 2. elongatus. 
B. Pelvics extending beyond origin of anal ; 28 to 30 scales in a 
longitudinal series. D. 17-19. A. 22-26. . . . 3. maculatus. 
■ 506 Mr. C. T. Regan— .4 Revision 
II. Pectoral fiti exteijcling beyond origia of anal. 
A. Dorsal origin behind that of anal, nearly equidistant from end of 
snout and base of caudal, or nearer the latter. 
D. 18. A. 20. 40 scales in a longitudinal series .... 4. porosus. 
D. 22. A. 24. 33 scales in a longitudinal series .... 5. robustus. 
p. 21-24. A. 26-30. 28 to 30 scales in a longitudinal 
series G. beUottii. 
J3. Dorsal origin a little in advance of that of anal, nearer tn end df 
snout than to base of caudal. D. 26. A. %o, 28 scales in a 
longitudinal series 7. nii/vipinnis. 
1. Cynolebias melanotce?iia, sp. n. 
Depth of body 3^ to 4^ in the length, length of head 3^ 
to 3i. Caudal peduncle longer thati deep. Diameter of 
eye 3 in the length of head. 28 scales in a longitudinal 
series. Dorsal 16-18, origin above that of anal, equidistant 
from some part of eye and base of caudal. Anal 17-20. 
Dorsal and aual rather elevated posteriorly. Pectoral 
shorter than head, not reaching anal ; pelvics small, not 
reaching anal. A blackish lateral baud from lower jaw 
through eye to base of caudal, another at base of anal con- 
tinued forward to base of pectoral, sometimes a third on the 
back ; vertical fins usually spotted. 
S.E. Brazil. 
1-9 (types). 32-37 miij. Paranagua. Rachow. 
2. Cynolebias elongatus. 
Cynolebias elongatus, Steind. Denkschr. Akad. Wien, xliv. 1882, p. 11. 
Depth of body 3^ in the length, length of head 3. Caudal 
peduncle longer than deep. Diameter of eye G in lengtii of 
head. 45 to 50 scales in a longitudinal series. Dorsal 17 ; 
origin equidistant from prjcoperculum and base of caudal ; 
posterior rays longest, ^ length of head. Anal 20 ; origin 
scarcely in advance of that of dorsal ; middle rays longest, 
rather shorter than longest rays of do)-.-al. Pectoral as long 
as postorbital part of head, extending to middle of pelvics, 
which reach the vent. Brownish ; a dark vertical bar 
through eye ; vertical fins spotted. 
La Plata. 
1. 140 mm. La Plata. Arnold, 
i 
of Pcecih'id Fishes. .007 
3. Cynolebias maculatus. 
Cynolehiiis macuhiUts, Steind. Denksc'ir. Akad. Wien, xliv, 1882, p. 10, 
pi. V. fig. 2 ; Garman, Mem Mus. Comp. Zool. xix. 1897, p. 145. 
Depth of body 3 in tlie length, length of head 3,^ to 2,?.. 
Caudal peduncle longer than deep. Diameter of eye tearly 
4 in the length of head. 28 to 30 scales in a longitudinal 
series. Dorsal 17-19; origin nearly above that of anal, 
about equidistant from eye and base of caudal ; posterior 
rays longest, | or 4 length of head. Anal 22-26 ; middle 
rays as long as longest of dorsal. Pectoral | length of head, 
extending to anterior part or middle of pelvics, which reach 
beyond origin of anal. Olivaceous; a dark stripe below 
eye ; vertically expanded violet spots on body and vertical 
fins. 
La Plata. 
1-3. 55-60 mm. I-a Plata, Doria. 
4, 47 mm. „ Arnold. 
4. Cynolebias porosus. 
Cynolebias porosus, Steind. Sitzungsb. Akad. Wien, Ixxiv. 1876, p. 173, 
pi. X. tig. 3; Garman, Mem. Mus. Comp. Zool. xix. 1897, p. 143. 
Depth of body nearly equal to length of head, about 3 in 
the length of tish. Caudal pedunc le nearly as long as deep. 
Diameter of eye 5 in length of head. 40 scales in a longi- 
tudinal series. Dorsal 18; origin equidistant from prse- 
operculum and base of caudal ; posterior rays longest, ? 
length of head. Anal 20 ; origin equidistant from anterior 
margin of eye and base of caudal ; posterior rays longest, 
nearly as long as head. Pectoral | length of' head, ex. 
tending beyond origin of anal ; pelvics extending beyond 
origin of anal. Brownish ; fins greyish. 
Pernambuco. 
Total length 75 mm. 
5. Cynolebias robustus. 
Cynolebias robustus, Giinth. Ann. & Mag. Nat. Hist. (5) ii. 1883, p. 140. 
Depth of body 2? in the length, length of head 3f. 
Caudal peduncle deeper than long. Diameter of eye 5^ m 
the length of head. 33 scales in a longitudinal series. 
Dorsal 22; origin equidistant from middle of eye and base 
of caudal ; posterior rays longest, ? length of head. Anal 
508 A Revision of Paeciliid Fishes. 
24 ; orio^in considerably nearer to end of snout than to bsae 
of caudal ; middle rays as long as longest of dorsal. Pectoral 
as long as postorbital part of head, extending beyond origin 
of anal. Brownish, with indistinct cross-bars : a dark bar 
below eye ; small pale blue spots on dorsal and anal fins. 
La Plata. 
1 (type). 92 mm, San Antonio. Gibson. 
6. Cynolebias bellottii, 
Cynolehias bellottii, Steind. Denkschr. Akad. Wien, xliv. 18S2, p. 9, 
pi. V. fig. 3 ; Garman, Mem. Mus. Comp. Zool. xix. 1897, p. 144. 
Depth of body 2^ to 3 in the length, length of head 3| to 
3§. Caudal peduncle deeper than long. Diameter of eye 4 
in the length of head. 28 to 30 scales in a longitudinal 
series. Dorsal 21-24 ; origin nearly equidistant from end 
of snout and base of caudal ; posterior rays longest, ^ to | 
length of head. Anal 26-30 ; origin about equidistant from 
end of snout and end of its own base ; middle rays as long as 
longest of dorsal. Pectoral | or f length of head, extending 
beyond origin of anal. Brownish; a dark vertical stripe 
through eye ; fins violet ; vertical series of pale spots some- 
times present on body and fins. 
La Plata. 
1-2. 65 mm. La Plata, Doria. 
3, Skel. 
4-5. 55-60 mm, ,, Arnold. 
7. Cynolehias nigripinnis, sp, n. m 
Depth of body 3^ in the length, length of head 3|. 
Caudal peduncle nearly as long as deep. Diameter of eye 
3vV in the length of head. 28 scales in a longitudinal series. 
Dorsal 26 : origin a little nearer to end of snout than to 
posterior end of its own base. Anal 25 ; origin a little 
behind that of dorsal. Dorsal and anal rays increasing in 
length posteriorly, the longest | the length of head. Pectoral 
a little shorter than head, extending beyond origin of anal. 
Olivaceous ; a dark bar between and below eyes ; fins bluish 
black ; some small pale spots on body and fins. 
La Plata. 
1 (type). 45 mm. La Plata. Arnold. 
♦