OF THE UNITED STATES. _ 43 
Say, which I have figured in Journ. Acad. Nat. Science, 
vol. vi. pl. v. fig. 6. 
The greatest diameter of one of my specimens is an 
inch and three-fourths; and they have been found five 
inches long. It is not uncommon in New Jersey, and 
occurs also in the Ferruginous sand of Delaware and Ala- 
bama. 
2. B. compressus, (Say) pl. ix. fig. 1. 
American Journal of Science, vol. ii, p. 41. 
Specific character. ‘“ Elongated, much compressed; trans- 
verse section oblong-oval, narrowed to each end; lobes dilated, 
dentated on their edges, with from three to five sutures on 
each side, and a profound one at tip.” 
Mr. Nuttall informed Mr. Say that this fossil is of fre- 
quent occurrence in the Missouri country, washed out 
from the banks of the Missouri river, between White 
river and the Mandan settlements. Mr. N. has seen 
them more than a foot long, and three or four inches 
broad at base. 
I regret that I have seen so few specimens of this fossil 
as not to have satisfied myself that it is distinct from B. 
ovatus. ‘The name compressus given it by Mr. Say is 
sufficiently descriptive, as will be seen by reference to the 
accompanying figure, which was drawn from a specimen 
lent me by J. P. Wetherill, Esq. 
3. B. asper, (S. G. M.) pl. i, fig. 12, 13, and pl. xiii, 
fig. 2. 
Specific character. Transversely suboval, with prominent 
circumscribed, lateral nodes, and numerous septa. 
