Sand^ Formation of the United States. 285 



at least, I refer the marl shells of this genus to the species just nam- 

 ed, to which they bear a strong resemblance. This anomia is abund- 

 ant in the blue marl at St. George's and other places in the vicinity. 

 It is also found near Arneytown, N. J. 



PECTEN. 



1. P. quinqueco status. (Sowerby.) If the American species is not 

 positively identical with the European, it is at least an obvious analo- 

 gue, and answers in almost every particular to the figures of Sower- 

 by and Brongniart. The last named naturalist makes the following 

 remarks on this species : " Ce peigne, qui parait presenter des varie- 

 tes assez nombreuses de dimensions, et meme de proportions dans les 

 dimensions, est une des coquilles les plus constantes dans les terrains 

 de Craie inferieurs.^^* 



2. A minute, flat shell, about half an inch in diameter, and having 

 from fifteen to twenty costse. It is of rare occurrence. 



CARDIUM. 



Casts of a smooth cardium are common in all the varieties of marl. 

 They vary in size from an inch to an inch and half, but have never 

 been found with any portion of the shell remaining. Casts, appar- 

 ently of this genus, also occur, very globose and strongly ribbed. 



CUCULL^A. 



1. C. vulgaris. (S. G. M.) Casts of this fossil occur abundantly 

 throughout our marl formation : no part of the shell, however, had 

 been found until very lately, when Mr. Wm. Riley obtained seve- 

 ral specimens sufficiently perfect for description. These will be fig- 

 ured in a subsequent part of this work. 



2. A large, globose cast, about two and a half inches in diameter, 

 is occasionally found in excavating the Chesapeake and Delaware 

 canal. 



ItfYA. 



Casts of shells about two inches long, with deep concentric sulci. 



TRIGONIA ? 



I possess a single cast of a shell apparently referrible to this genus. 

 It will be interesting to decide this question, when other and more 

 perfect specimens may have been obtained. 



" Desciip. Geol. &c. p. 385, edit. 1822. 



