34 CYMBA. 
elongated, compressed, laminar, acute, doubled in the left valve, 
ligament external; epidermis thin, horny. Obs. The Cyclades 
are viviparous, and abound in ditches, ponds, slow streams, &c. 
in Europe and North America. The genus Pisidium has been 
separated on account of a difference in the animal, and may 
be known from Cyclas, by being less equilateral, and the 
anterior side being the widest. Fig. 111,C. Rivicola. 
CYCLOBRANCHIA’TA. Bl. Third order of the second sec- 
tion of Paracephalophora Monoica, Bl. containing no genera of 
Testaceous Mollusca. 
CYCLOPHORUS. Montf. Generic name proposed for those 
species of Cyclostoma, Auct. which have an umbilicus. C. 
Involvulus, fig. 304, would be the type of this genus. 
CY’CLOPS. Montf. Nassa Neritoidea, Auct. fig. 424. 
CYCLOS'TOMA. Lam. (Kixdos, cyclos, round; Sropa, stoma, 
mouth.) Fam. Colimacea, Lam. Cricostomata, Bl. Deser. 
Turbinated, globose, or oval, with an obtuse apex; rounded 
whorls and circular aperture, more or less angulated towards 
the spire; peritreme uninterrupted, thickened and reflected; 
operculum horny, spiral. Obs. All the Cyclostomata are land 
shells, mostly of tropical climates, but there are two or three 
European species. Fig. 303. C. ferrugineum; fig. 304, C. In- 
volvulus. 
CY’LINDER. Montf. Conus Textile, Auct. fig. 461, and other 
species having a cylindrical form. 
CYLINDRICAL. (KvdwSpor, cylindron, a cylinder.) This, like 
other mathematical terms, is used with great latitude by 
conchologists, and applied to any shell the body of whichis — 
somewhat straight, with the ends either rounded, flat or conical. 
Ex. Oliva, fig. 457. 
CYLLENE. Gray. Fum. Columellaires? Lam. Deser. Oval, 
thick, with a short acute spire; an oval aperture terminating an- 
teriorly in a slight emargination, posteriorly in a short canal; 
a fold at the lower end of the body whorl; inner lip smooth, 
spread over part of the body whorl; outer lip thick, striated 
within; angle of the whorls tuberculated. Obs. This genus 
of small marine shells resembles Voluta in general character, 
but differs in having a smooth columella without folds. 
Fig. 425. 
CYMBA. Brod. (Cymba, a boat or skiff.) Fam. Columellaria, 
Lam. Descr. Smooth, ventricose, with a very short, mammil- 
lated, rude spire; and a very large, wide aperture, terminated 
anteriorly in a deep emargination; posteriorly in a flat ledge, 
which separates the outer lip from the body whorl; columella 
with three or four oblique, laminar, projecting folds, terminating 
in a point; outer lip thin, with its spiral edge sharp; epidermis 
smooth, brown, covered partly or entirely by the glassy enamel, 
