4 
15 
cated, and the front obtuse : in many specimens the 
margin of the larger valve, which is always a little bent, 
is protruded in the form of a lip beyond the anterior side 
of the other valve : I say in many specimens, because I 
have a considerable number that differ in no other respect 
than the want of this lip ; they can hardly be younger, as 
they are mostly of the same, or even of a larger size. 
Very abundant in the blue clay of Highgate Hill, fre- 
quently in clusters ; and I have never met with a divided 
pair. 
CORBULA PIsum. 
TAB. CCI X.—Fig. 4 . 
Spec. Char. Subglobose, irregular, concentrically 
furrowed ; anterior side slightly truncated ; 
margin of one valve produced ; beaks unequal 
A rugged looking shell ; the beak of the larger valve is 
very prominent, evenventricose, especially in oldsubjects ; 
the expanded margin extends beyond the anterior side of 
the smaller valve, and a considerable part of the front. 
The furrows are commonly worn away ; which circum- 
stance, together with some irregularity in the shape, give 
it the aspect of a shell that inhabits holes in stone. 
Several of my correspondents have favoured me with 
this from Barton and Hordle Cliffs : among others Miss 
Bennett, the Rev. Mr. Iremonger, and the Rev. Mr. 
Bingley, wherefore I suppose it is a very common species 
there, although not noticed by Brander. 
