191 
UNIO crassiusculuso 
TAB, CLXXXV. 
Spec. Char. Obion g-elli plica], depressed ; valves 
thick ; surface marked by lines of growth ; 
hinge strong. 
The surface of this shell is regularly curved, without 
any hollow or rising : the beaks are sharp, a little re- 
curved : the lines of growth are not very prominent^ 
except two or three of them near the edge : the hinge is 
light and elegant in comparison to that of U. crassissh 
mus, although thick. 
I atn indebted to the Rev. G. R. Leathes for the know- 
ledge of this Unio : he has obtained it from the Craig at 
Bawdesey, in Suffolk. 
The valves have been replaced by carbonate of lime 
of a crystalline texture, and are attached to masses of 
ochraceous limestone, or lie loose in the craig. 
