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.) pi. i. 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 l-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. It is 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. 



