76 CRETACEOUS GROUP 



Cassidulus, Lam. 



C. sequoreus, (S. G. M.) PL iii, fig. 14. 



Specific character. Compressed, suboval, with five ambu- 

 lacra, consisting of two pairs of dotted lines arranged elliptic- 

 ally; anus large, above the margin; base concave, delicately 

 dotted or tuberculated ; mouth nearly central, pentangular. 



Long diameter, one inch. 



From the Ferruginous sand of 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. iii, fig. 12, and pi. x/ 

 fig. 12. 



Specific character. Very convex or subcorneal; 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. geomelricus, (S. G. M.) PI. x, fig. 9. 



Specific character. Hemispherical; ambulacra elevated, 

 formed of two pairs of lines connected by transverse strise ; 

 mouth stelliform, with five radiating ridges that pass the mar- 

 gin, and become continuous with the ambulacra. 



Occurs in the canal excavations of Delaware. 



