34 - GRETACEOUS GROUP 
1. B. Americanus. (S.G. M.) PI. i. fig. 1, 2, 3, 3a. 
Journ. Acad. Nat. Sc. vol. vi, pl. viii. fig. 1, 2,3; Amer. 
Journal of Science, vol. xviii, pl. i. fig. 1, 2, 33° Journ. 
Acad. Nat. Sc., vol. vi. pl. v. fig. '7; Mitchell, Amer. ed. of 
Cuvier’s Theory of the Earth. 
Specific character. Sub-cylindrical, with a slight contraction 
towards the base, which gently expands: base marked by nu- 
merous deep, ramose furrows, at first directed obliquely up: 
wards, but becoming longitudinal as they approach the apex, 
giving the surface a coarsely granulated appearance. In the 
base is a fissure extending about one-fourth of the length of the 
shell, and communicating with a conical, subcentral chamber, 
marked with concentric circles. On the back is a distinctly 
elevated plane surface, narrow towards the base, and expand- 
ing gradually towards the apex, where it becomes indistinct. 
Color, clove brown; translucent. 
Var. A. Subfusiform, Pl. i, fig. 3. 
Var. B. Chambet‘ small, body flattened, apex obtuse. 
P). i, fig. 3a. 
Var. C, Slender, tapering, pointed. Pl. xvii. fig. 2. 
Whether these varieties of form are specific or acci- 
dental, I will not at present attempt to decide; but when 
it is recollected that M. de Blainville has described 
nearly fifty species of European Belemnites, we may rea- 
sonably suspect that our own are not limited to a single 
species. 
This species has an analogue in B. mucronatus of Ku- 
rope, (Blainville, Mem. sur les Belemnites, pl. 1. fig. 12 5 
Sowerby, pl. 600. fig. 1, 2,4, 6 and 7.) Abundant in 
the arenaceous marls of New Jersey, Delaware, North 
Carolina and Georgia. In some of its localities it is pro- 
