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. quinquecostatus. (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- 
tés assez nombreuses de dimensions, et méme de proportions dans les 
dimensions, est une des coquilles les plus constantes dans les terrains 
de Craie inferteurs.””* 
2. A minute, flat shell, about half an inch’ in diameter, and having 
from fifteen to twenty coste. 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. 
CUCULLZA. 
I C. vulgaris. (S..G.M.). Casts of this Soil opear sbundantiy 
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. exeavating the Chesapeake and Delaware 
canal, 
“aia. 
‘Casts of shells abdiat ksets inches long, with deep concentric aut 
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 
Specimens may have been ApaDeN: qodiondue 
* Descrip. Geol. &c. p. 385, edit. 1822. 
