280 PALEONTOLOGY OF NEW JERSEY. 
Order DIBRANCHIATA. 
Genus BELEMNITELLA D’Orbigny. 
BELEMNITELLA AMERICANA. 
Plate xLvi, Figs. 1-11. 
Belemmites Americanus Morton: Jour Acad. Nat. Sci., Phila., 1st ser., vol. 6, p. 
190, Pl. v1, Figs. 1-3, and Pl. v, Fig. 7; Am. Jour. Sci., vol. 18, Ist ser., 
p. 249, Pl. 1, Figs. 1-3; vol. 17, p. 281; Synopsis, p. 34, Pl. 1, Figs. 1-3. 
Belemnites subconicus (Lam.) Morton: Jour. Acad. Nat. Sci., Phila., vol. VI, pp. 
91 and 100, Pl. v, Fig. 7. 
Belemnitella mucronata (Schlot.) D’Orb.: Prod. Paléont., tome 2, p. 211; Gabb, 
Synopsis, p. 22; Meek, Geol. Surv. N. J., 1868, p. 731. 
Belemnitella subfusiformis Morton : Synopsis, p. 34, Pl. 1, Fig. 3. 
? Belemnitella pawxillosa Meek: Geol. Surv. N. J ., 1868, p. 731. 
Stylet or guard rather large, solid and heavy, often becoming thick- 
ened with age so as to be proportionally much larger in diameter as com- 
pared with smaller individuals. Specimens. varying from 3 to nearly 4 
inches in length below the base of the slit, the larger ones evidently having 
a length of fully 6 inches from the lower extremity to the top of the internal 
cavity or conotheca. General form triangularly cylindrical in the upper 
part, becoming flattened on the ventral side in the lower part, with frequently 
a slight mucronate extremity, which when broken generally shows a slight 
central perforation, as do many of those which are destitute of this pointed 
extremity. In many old examples the extremity is solid as in the specimen 
Fig. 3, Plate xivu, while in the largest individual which I have observed 
from New Jersey, Figs. 5, 6, and 7, there is yet a slight perforation. Ihave 
never seen the mucronate point exceeding one-sixth of an inch in length. 
The upper end of the stylet or guard, from about the base of the internal 
cavity, gradually expands upward and becomes very thin on the edge, and 
the inner surface of the wall often bears the marks of the transverse septa 
of the phragmocone. At about the base of the cavity the external diame- 
ter is less than below, and in some examples the lower portion is consider- 
ably expanded as in the one represented by Figs. 1 and 2, Plate xivn, 
which is the typical specimen of Dr. Morton’s var. a, B. subfusiformis, while 
in others there is almost a regular decrease downward to near the extremity, 
which is usually obtusely rounded except for the mucronate point occasion- 
