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instances, succeeded by granite. In another direction, they are lost 
in the lime- stone rocks of Chudleigh. 
The stratum of shells, Mr. Scammell observes, exists in a stratum 
of greenish yellow sand, about five feet below the surface ; and he is 
able, from repeated and careful observation, to state that these fossil 
shells extend upwards of four miles. 
The shells, from their extreme brittleness, are almost all in small 
fragments. Mr. Scammell having, however, kindly furnished me 
with some of the largest, I was enabled to ascertain that they were 
the remains of several species of Pectens, of a small oblong oyster, 
and of a shell, in which, although the characters of a chama were 
predominant, only one mark of attachment was discoverable. 
The general form of this shell is very much like that of the chamse 
we have been just describing ; the outer surface is pretty smooth, 
being only marked by faint transverse striae. The hinge is formed 
by an oblique, moderately sized, and slightly crenulated tooth, on the 
flat valve, which is received by an oblique groove, with corresponding 
crenulae on the convex valve. 
CXXXIV. Spondylus. A rough, slightly-eared, inequivalved 
bivalve, with unequal beaks ; the inferior more produced, truncated 
upwards, and with one groove. The hinge with two thick recurved 
teeth, with an intermediate pit for the reception of the cartilage. 
One muscular impression. 
Lamarck describes only one species, £.ra(/«Za,asfoundintheenvirons 
of Paris. A fossil shell of this genus, which, from the appearance ot its 
matrix, I suspect to be from Worcestershire, agrees, except in its size 
being one third larger than the French fossil, with the species described 
by Lamarck. It is slightly eared, and the inferior valve is marked 
with rough longitudinal striae. It is rough, oblique, and of an oval 
orbicular form. The stronger and most raised of the striae of the lower 
valve have small spinous squamae placed at about half an inch distant ; 
these striae being separated by from six to nine small granular striae. 
