51 
CYCLAS pulcher. 
TAB. DXXYll.—fg. 1. 
Spec. Char. Suborbicular, convex, smooth, slen- 
der ; posteriorly truncated ; one sharp-edged 
and two bifid teeth near the beaks in each 
valve ; lateral teeth plain, obtuse. 
A thin shell in proportion to its size, which much ex- 
ceeds that of any other British species ; the angular form 
of its posterior portion is a conspicuous character. 
This species belongs to Lamarck’s Genus Cyrena ; 
but as we have much doubt of that being a natural di- 
vision, we do not at present adopt it. 
A discovery, for which we are indebted to the un- 
wearied research of Professor Sedgwick, who found it 
in abundance on the shore opposite Hampstead Cliff, 
Isle of Wight, at low water, in a stiff clay, accompanied 
by a small Cyclas, a striated Mytilus, Potamides ventri- 
cosus, (t. 341. f. 1.) Melanopsis carinatus, several small 
univalves, and a Serpula, — all together forming a curious 
mixture of apparently marine and fresh- water shells. 
CYCLAS medius. 
TAB. DXXYII. —Jig. 2. 
Spec. Char. Transversely obovate, depressed, 
thick, smooth ; anterior side small ; posterior 
rather pointed ; one tooth near the beaks in 
each valve. 
Syn. Cyrena media. Annals of Phil. New Series , 
vol. 8 .p. 376, 378, 379. 
Intermediate between Cyclas obovatus and C. cunei- 
formis, (tab. 162.) being flatter and thinner than the first, 
