65 
LUTRARIA ? striata. 
TAB. DXXXI y.—fig. 1. 
Spec. Char. Transversely oval, compressed, con- 
centrically striated ; posterior side smallest, 
rather pointed, gaping ; umbones prominent. 
A small shell, about two-thirds as long' as wide : the 
superior margin of the posterior side is rather produced 
and turned outwards; the surface is marked by nume- 
rous concentric striae. 
Found in the Greensand near Lyme Regis, by H. 
T. De la Beche, Esq., in whose cabinet the specimen is 
preserved. The shell is almost lost, only a film of pow- 
der remaining upon the surface of the cast. 
This and the two following fossils are very similar to 
some recent species of the genus Anatina, — a genus with 
the limits of which we are not sufficiently acquainted to 
be able to arrange shells under it, without the help of 
the hinge, in the form of which the principal difference 
from Lutraria rests *. 
* In many of the species, and perhaps in all, if the genus 
were confined within its proper limits, there is a loose appendage 
to the hinge. 
