993 
Ad 
PILEOPSIS.—Lamarck. 
Gen. Cuar. Shella recurved cone covering the 
animal ; the apex turned backward and to the 
right, minute, involute ; muscular impression 
posterior, arched, its extremities dilated. 
A genus formerly included under Patella, now evidently 
well separated from it, even if only its own characters 
independent of those of its animal be considered: but 
when the situation of the branchiz in a distinct cavity 
near the head, and the connection of the mantle with the 
shell are observed, no doubt can be entertained. It is 
more difficult to distinguish Hipponix from it when the 
secondary valve (or support as M. De France calls it) of 
that genus is absent: indeed Lamarck has made Hipponix 
only a section of the genus Pileopsis ; the form and posi- 
tion of the apex seem to indicate a difference. 
Patella Unguis (t. 139. f. 7. & 8.) belongs to this genus. 
There are also two or three recent species known ; one, 
P. ungarica, is British, it is covered with a fringed epi- 
dermis. 
The Fossil species are only in the oldest and newest 
conchiferous formations. 
PILEOPSIS vetusta. 
TAB. DCVIL—figs. 1. 2. & 3. 
Spec. Cuar. Smooth, contracted posteriorly ; two 
or three irregular undulations rise up the front; 
margin sinuose. 
Tur sides of this shell being rather flattened, the ovate 
