136 THE NAUTILUS. 

being less elongated and more inflated with more prominent beaks. 
The color both of the epidermis and nacre is also quite different. 

Messrs. Frierson and Marsh, to whom specimens have been sub- 
mitted, agree that it is distinct from any described fo:m, and Mr. 
Simpson remarks that it <k looks more or less like two or three species, 
but I cannot refer it to anything." Mr, B. H. Wright suggests that 
it is close to some forms of U. confertus Lea, but both in shape and 
color, which is remarkably constant in all the specimens seen, it 
seems sufficiently distinct. 

UNIONIDAE FROM MOCCASIN CREEK, A TRIBUTARY OF THE 
ECONFINE RIVER. 

Lampsilis anodontoides floridensis Lea. 
" lienosus Con. (caliyinosus Lea). 
" vibex Con. (i-utilans Lea) v 

Unio' downiei Lea, var. 

arctatus tortivus Lea. 

A very large, heavy, inflated form similar to Lea's tetricus, longer 
but not so swollen as that figured by Simpson in Proc. U. S. Nat. 
Mus. xv. PI. Ixiv. figs. 3 and 4. Associated with this form is an- 
other more compressed, strongly rayed and with umbonal slope, 
decidedly biangulate, which Mr. Simpson thinks is also referable 
here. Mr. Marsh considers this identical with Wright's nolani, a 
synonym of the following species. 

Unio obnubilis Lea. Two specimens smaller, thicker and appar- 
ently quite distinct from the last-mentioned form are referred to 
santeensis Lea, by Marsh, to which Simpson somewhat doubtfully 
assents. 

A NEW SPECIES OF MEDIONIDUS. 

BY BRYANT AVALKER. 

Medionidus sirupsonianus n. sp. PI. ix. figs. 4 and 5. 

Shell small, rather thin, somewhat inflated, elliptical, inequilateral, 
strongly plicate on the posterior slope. Epidermis dark yellow, 
smooth, polished, covered with dark green pencilled rays which tend 
to break into a net-work of angular lines covering the entire surface. 
Anterior end compressed, rounded, and slightly elevated above the 

TIII; NAUTILI'S. 137 

line of the hinge superiorly ; posterior extremity obtusely rounded, 
the tip being nearly on the median line of the shell ; posterior ridge 
somewhat angled ; dorsal slope covered with strong sub-concentric, 
somewhat irregular ridges extending from the posterior ridge to the 
margin; basal margin regularly curved; hinge margin nearly 
straight, slightly angled between the cardinal and lateral teeth. 
Cardinal teeth crenulate, erect, rather compressed, those in left valve 
nearly on the same line ; lateral teeth slender, straight and nearly 
smooth. Anterior cicatrices well impressed, posterior cicatrices 
distinct, dorsal cicatrices under the plate behind the cardinal teeth. 
Beak cavity rather shallow, cavity of the shell deep and uniform. 
Nacre bluish-white, rather thicker anteriorly. 

Length 36; height 19, width 13 mm. 

Habitat, Calvary, Ga. 

Only three specimens of this little species were received, and these, 
unfortunately, without any information as to the stream where they 
were found. 

This species belongs to the " conradicus " group of Medionidus as 
defined by Simpson, and is most nearly related to M. penicillatus. 
But it differs decidedly from all the described species in the com- 
pression of the anterior end, the elevation of the superior-anterior 
margin and the regularly rounded posterior margin, which is equally 
curved above and below, the tip being nearly on the median line and 
not depressed toward the basal margin as in all the allied species. 
The ridges on the posterior slope are cpjite as strong, but not so 
numerous as in M. kinyii. 

It is named in honor of Mr. Charles T. Simpson, whose recent 
retirement from active conchological work has been a source of regret 
to all interested in American Conchology. 

A NEW LOCALITY FOR CEEION INCANUM. 

BY CHARLES T. SIMPSON. 

I have just returned from a visit to " Baker's Haulover," the nar- 
row strip of land between the extreme upper end of Biscayne Bay, 
Florida, and the Atlantic. This strip may be twenty rods wide, is 
low and covered with mangroves on the inner side, and next the 
ocean is sand-bank twelve or fifteen feet high with shore grapes, low