118 CONTRIBUTIONS 
furrow, smaller striz may be perceived. In the umbilicus 
the striz on the inferior part of the whorl are longitudinal 
—on the superior part transverse. The two carine cause 
the lip to be slightly angular. 
D. depressa. Plate 4. Fig. 105. 
Description. Shell sublenticular, polished, obsoletely 
and transversely striate, substance of the shell thick ; spire 
depressed ; suture slightly impressed ; umbilicus rather 
small, thickened and wrinkled at the edge ; whorls three; 
mouth subelliptical. 
Length nearly .1, Breadth .2, of an inch. 
Observations. Of this curious and interesting little 
species, I have procured but a single specimen. Its 
smoothness and general form are very unusual in this 
genus. Its lenticular form causes the mouth to be some- 
what oval. A small portion only of the lip is perfect, and 
it seems to be thickened and somewhat reflected. 
De la Beche mentions an undetermined species as ex- 
isting in Yorkshire, as low down as the Oolitic Group. 
Sowerby does not describe any, in his ‘ Mineral Con- 
chology.” M. Deshayes, in his excellent Tables, gives 
twelve for the Tertiary. There are eight in the Paris 
basin, and five in the London basin. 
I believe none have been heretofore observed in our de- 
posits. vt 
