OF THE UNITED STATES. 35 
bable that hundreds of individuals might be collected in 
the compass of a few cubic feet. 
In a paper published in the Journ. Acad. Nat. Science, 
several years ago, I referred the American Belemnites to 
Lamarck’s species, B. subconicus, chiefly from an unwil- 
lingness to multiply specific names. In a later number 
of that work I have examined these remains with more 
scrutiny, and with the results here stated. Mr. Man- 
tell, to whom I have sent specimens, agrees with me in 
considering the American Belemnite a new species. 
2. B.? ambiguus, (S. G. M.) pl. 1. fig. 4, 5. 
Specific character. Straight, elongated, quadrangular, 
striated longitudinally ; front convex; back flat; sides slightly 
depressed by a longitudinal groove; apex obtuse, obscurely 
stellated; color yellowish white, opaque; substance, radiated 
carbonate of lime. 
Length 2 inches; breadth 1-6th of an inch. 
The specimens present some variety in the proportions of 
their sides, but the preceding characters will apply to most of 
them. | 
I always suspected this singular fossil to be a Belemnite, 
and especially after referring to the “‘ Memoire sur les 
Belemnites” of M. de Blainville. The B. cylindricus 
of that author appears to be the analogue of the Ameri- 
can species; the latter differing chiefly in the distinct- 
ness of its lateral grooves. Itis observed of the B. cylin- 
dricus, that it has rarely been observed with any trace of 
either a chamber or terminal extremity. My specimen 
shows the latter, but not the former; and the numerous 
individuals in the collections of the Academy are desti- 
tute of both. 
