34 CRETACEOUS GROUP 



1. B. Americanus. (S. G. M.) PI. i. ft%. 1, 2, 3, 3a. 



Journ. Acad. Nat. Sc. vol. vi, pi. viii. fig. 1 , 2, 3 ; Amer. 

 Journal of Science, vol. xviii, pi. i. fig. 1, 2, 3 ; Journ. 

 Acad. Nat. Sc, vol. vi. pi. 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. 



Far. A. Subfusiform, PI. i, fig. 3. 



Var. B. Chamber small, body flattened, apex obtuse. 

 PI. i, fig. 3 a. 



Var. C, Slender, tapering, pointed. PI. 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 Eu- 

 rope, (Blainville, Mem. sur les Belemnites, pi. i. fig. 12 ; 

 Sowerby, pi. 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- 



