IBS 
INOCERAMUS concentricus, 
TAB. CCCV. 
Spec. Char. Un equal valved, ovate,, one of the 
beaks much produced, incurved. 
Syn. Inoceramus concentricus. Parkinson in 
Trans . Geol. Soc . vol. V. p. 58. t. l.f. 4. 
Birostrina laevis. Jean Andre De Luc , M. S, 
One of the calves of this shell is rather deeper than the 
other, and has an acute, produced, incurved beak ; the 
beak of the other is very short ; both are transversely 
striated and undulated ; the strias are the edges of 
distant imbricated plates ; the length is nearly double 
the width : the hinge is straight, containing about a 
dozen grooves for the reception of the ligament : the 
shell is composed of two coats, the outer brownish and 
of a fibrous structure, the inner pearly. There is appa- 
rently no sinus for the passage of a Byssus. 
Found abundantly in the dark coloured blue Marl at 
Folkstone, and also in blue Marl of a lighter colour 
near Lewes in Sussex. Figures 1, 2, and 3, shew 
portions of the hinge. 
Miss Curtis was so kind as to favor me in 1813 with 
the first specimen in which I saw the hinge ; I have not 
since seen better, and should have figured it long ago, 
but did not wish to be too precipitate. It was found 
at Folkstone. 
I defer giving the characters of the Genus Inoceramus, 
until I figure the species found in Chalk, which 1 have 
named Cuvieri, in a paper read before the Linnean 
Society in 1814. I must observe however, that it differs 
from Perna in not having a sinus for the passage of a 
Byssus. 
