194 
A very handsome fossil shell, apparently of this genus, is found in 
the cliffs at Bognor ; but as I have never been able to view the inte- 
rior part, although I have destroyed several specimens for the purpose, 
I am unable to speak decidedly with respect to it. Fragments of the 
hinge part of a shell of this genus, are sometimes found in the neigh- 
bourhood of Norwich. 
CXXVI. Pcmopcea. A transverse inequilateral bivalve, gaping 
unequally at the ends. The hinge similar in both valves, having a large 
elongated tooth placed under thecartilaginal depression, running along 
the interior edge in a raised blunt margin, and projecting posteriorly ; 
a conical hinge-tooth, rather flat and bent ; and on the right valve, a 
little pit, which receives the tooth of the opposite valve. The ligament 
exterior ; the beaks but little projecting ; the depression large. Two 
muscular impressions in each valve, towards the extremities. 
This genus was formed by M. Menard de la Groye, on a shell found 
in Mount Pulgnasco, in the commune of Diolo, in Parma, in a fine- 
grained quartzose sand, mixed with a greyish clay. Of this shell, some 
beautiful specimens have been collected by M. Cortezi, of Parma. On 
clearing the hinge from one of these, which had been presented to M. 
Faujas, M. Menard was very much surprised to find that it was a shell 
of a mixed genus, resembling both Mya and Solen. This shell is 
about three inches and eight lines in length, and six inches and three 
lines in width. The outside is smooth, being only transversely grooved 
by the successive additions of new shell. On the inside, along the 
edge, and particularly the upper edge, is a callous smooth kind of 
border; and, further into the cavity of the shell, is another surface, 
more or less rugose, which marks the parts where the animal was 
attached. Annales du Mus. Tome ix. p. 131. 
A recent shell of this genus, but undoubtedly of a different species 
from the fossil shell described by M. Menard, has long been known to 
the conchologists. It was first figured by the indefatigable Aldrovandus, 
who gave to it the name of Chama glycemeris, Testae, lib. in. p. 472. 
