18 
AVICULA ovata. 
TAB. DXI.—fig. 2. 
Spec. Cuar. Transversely ovate, convex ; poste- 
rior side elongated, blunt ; hinge line long, 
forming part of the posterior wing, which is 
not distinct. 
A suicurty curved shell, much approaching in form to 
a Gervillia ; the hinge line occupies more than half the 
width of the shell: the wings do not project beyond it, 
but are rectangular, and raised upon the upper edge of 
the shell; the beaks are rather prominent. 
This may easily be taken for a short variety of Gervil- 
lia acuta (tab. 510.): but we can detect no indications of 
lamellar teeth or cavities in the hinge. Itisa species 
that connects the two genera. 
A very abundant shell in the Stonesfield Slate. 
