56 
GLYCIMERIS Vagina. 
TAB. DCXXXVI. 
Spec. Char. Transversely oblong-ovate,, com- 
pressed, smooth ; the anterior portion much 
the larger, rather attenuated and slightly con- 
vex ; the posterior flattened, truncated, more 
or less angular. Width to the length as 7 to 3. 
Syn. Glycimeris Vagina, Wood in Ann. and Mag. 
Nat. Hist. v. 6. 245. Morris , Catal. 88. 
The different degrees of convexity of the two parts of this 
shell, which give to each valve when separate a peculiar 
twisted appearance, and the great distance of the umbones 
from the anterior extremity, will at first sight serve to di- 
stinguish it from the recent G. Siliqua , which is the only 
species at present known that resembles it. The rectan- 
gular form of the fulcra, and the angular, not rounded, 
outline, are additional characters. Neither does it appear 
to have the umbones eroded, as they generally are in G. 
Siliqua , and in many shells of the northern seas, as well as 
in those which live in lakes and freshwater rivers : it pro- 
bably lived in a temperate climate, or at least in a situation 
where vegetable substances were not decaying around it. 
From the coralline Crag of Ramsholt, in the cabinets 
of the Rev. R. Wilson and 8. V. Wood, Esq. ; the latter 
gentleman has also traced it in the red crag of Sutton. 
