76 CRETACEOUS GROUP 
Cassipuuus, Lam. 
C. equoreus, (S.G. M.) PI. ui, fig. 14. 
Specific character. Compressed, suboval, with five ambu- 
lacra, consisting of two pairs of dotted lines arranged elliptie- 
ally; anus large, above the margin; base concave, delicately 
dotted or tuberculated; mouth nearly central, pentangular. 
Long diameter, one inch. 
From the Ferruginous sand cf Prairie Bluff, Alabama. 
Mr. T. A. Conrad. 
The differences between Nucleolites and Cassidulus are 
scarcely sufficient to warrant generic distinctions; but I 
place this fossil with the latter, in accordance with the 
views of Lamarck and others. 
CLYPEASTER, Lam. 
1. C. florealis, (S.G.M.) PI. iu, fig. 12, and pl. x, 
fig. 12. 
Specific character. Very convex or subconical; each of the 
five ambulacra composed of two pairs of finely dotted lines ; 
base suboval, concave; margin abrupt. 
The specimen figured is a finely preserved cast, from 
the Ferruginous sand of the Delaware and Chesapeake 
canal. 
2. C. geometricus, (S.G. M.) Pl. x, fig. 9. 
Specific character. Hemispherical; ambulacra elevated, 
formed of two pairs of lines connected by transverse striz ; 
mouth stelliform, with five radiating ridges that pass the mar- 
gin, and become continuous with the ambulacra. 
Occurs in the canal excavations of Delaware. 


