CYCLAS. 33 
CRYPTODIBRANCHIATA. Bl. The first order of the class 
Cupuatopnora, Bl. containing genera of molluscous animals 
destitute of shells. 
CRYPTOSTOMA. Bl. Differs from Sicarerus, Lam. princi- 
pally in the soft parts of the animal. 
CUCULLASA. Lam. (Cuculus,a hood.) Fam. Arcacea, Lam. 
Descr.Sub-quadrate, nearly equivalve,sub-equilateral, deep ; hinge 
rectilinear; withaseries of angular teeth, small near the umbones, 
larger and more oblique towards the extremities; umbones 
separated by aflat external area, on which the ligament is spread. 
Anterior muscularimpression, produced intoa sharp-edged plate 
or ledge, projecting from the side of the shell. Posterior muscular 
impression, flat and indistinct. Obs. Thisgenus very much resem- 
bles Arca in general form, but differs in the oblique, lengthened 
character of the remote teeth, andin the singularly prominent 
edge of the muscular impressions. Fig. 133, C. Auriculifera. 
CUCUMIS. Klein. Mareiner’ta, Auct. 
CUMIN’GIA. Sow. Fam. Mactracea, Lam. Descr. Equivalve, 
inequilateral, transverse, rounded anteriorly, sub-rostrated pos- 
teriorly. Hinge with a central, spoon-shaped cavity in each 
valve, containing the cartilage, a very small anterior cardinal 
tooth in each valve, two lateral teeth in one valve, none in the 
other. Muscular impressions two in each valve, distant; palleal 
impression with a very large posterior sinus. Obs. The species 
known at present are found in sand, in the fissures of rocks of 
tropical climates. They are like Erycina in general form and 
character, but differ in the dissimilarity of the hinge in the two 
valves. This genus should be placed near Amphidesma. Fig. 87. 
C. mutica. 
CU'NEIFORM. (Cumeus, a wedge.) Wedge-shaped, as Donax, 
fig. 108. 
cuN EUS. Megerle. Vunus Meroe, Linn. and similar species. 
CURVULA. Rafinesque. A fossil imperfectly described as differ- 
ing from Pinna, in being inequivalve. 
CUTEL'LUS. Species of Lurraria, Lam. which have the um- 
bones placed near the extremity of the shell. Ex. L. Solenoides, 
fig. 78. 
CUVIERIA. Ranz. (Baron Cuvier.) Class. Pteropoda, Lam. 
Descr. Thin, transparent, glassy, cylindrical, rounded and in- 
flated at the closed extremity, compressed towards the opening, 
so as to render it oval. This genus differs from Vaginula in 
being rounded, instead of pointed, at the lower extremity. Fig. 
223, C. Columella. 
CY’CLAS. Brug. Fam. Conques Fluviatiles, Lam. Concha- 
cea, Bl. Descr. Orbicular, thin, subovate, ventricose, sub-equi- 
lateral, equivalve; cardinal teeth minute, one more or less com- 
plex in the left valve, two diverging in the right; lateral teeth, 
F 
