336 
ELEMENTS OE GEOLOGY. 
Fig. 314. 
Cardium dissimile. ^ uat. size. 
Portland Stone. 
Fig. 315. 
Ostrea expansa. Portland Sand. 
may perhaps be of animal origin. Some of the sanrians (Pli- 
osaurus) in Dorsetshire are among the most gigantic of their 
kind. 
Among the fossils, amounting to nearly 100 species, may 
be mentioned Cardium striatidum (Fig. 316) and Ostrea del- 
toidea (Fig. 317), the latter found in the Kimmeridge Clay 
throughout England and the north of France, and also in 
Fig. 316. Fig. 31T. 
Kimmeridge Clay, Ostrea deltoidea. 
Hartwell. Kimmeridge Clay, i nat. size. 
Fig. 318. 
Gryphcea (Exogyra) 
virgula. 
Kimmeridge Clay. 
Scotland, near Brora. The Gryphcea virgula (Fig. 318), also 
met with in the Kimmeridge Clay near Oxford, is so abun¬ 
dant in the Upper Oolite of parts of France as to have 
caused the deposit to be termed “ marnes a gryphees vir- 
gules.” Near Clermont, in Argonne, a few leagues from St. 
Menehould, where these indurated marls crop out from be¬ 
neath the gault, I have seen them, on decomposing, leave 
the surface of every ploughed field literally strewed over 
Fig. 319. with this fossil oyster. The Trigonellites la^ 
tus [Aptychus of some authors) (Fig. 319) is 
also widely dispersed through this clay. The 
real nature of the shell, of which there are 
many species in oolitic rocks, is still a matter 
_ . , of coniecture. Some are of opinion that the 
Park, Kimme- two plates have been the gizzard ot a ceph- 
ridge Clay. alopod; Others, that it may have formed a 
bivalve operculum of the same. 
