CEPHALOPODA. 37 
lateral expansions are inclined towards the ventral aspect, and give a convex form to 
the dorsal surface, and a corresponding concavity to the ventral surface; they 
are thick at the juncture of the rostrum and sheath, and become gradually thinner as 
they enlarge, presenting a sharp cutting edge on their free outward margins. In this, 
the typical species, they are largely developed, regular in form, and vary considerably 
in size according to the age of the individual; in young specimens they present an 
elongated semielliptical form, which, as the shell advances towards maturity, becomes 
nearly semicircular. 
Figs. 1f and lg represent a variety in which the inferior cone is shorter, broader, 
and more compressed, and the wings are wider than in the ordinary specimens. 
The B. Belemnitoidea is found in England at Bracklesham Bay, where it is some- 
what rare. In France it is found in the nummulitic bed at Biaritz, in the Lower 
Pyrenees ; the lower beds of the calcaire grossier at Vivrais, Grypseuil, and Pouchon 
(Oise), and, in the middle beds, at Grignon, Parnes, Muchi-le-Chatel, Chaumont, &c. 
It also occurs in Belgium, in the sandy beds at Laeken. 
The size is eleven lines in length, and four lines and a half in width across the widest 
part of the lateral expansions. 
No. 5. BrLopTera LeEvEsQuE!. D'Orbigny. Tab. 2, fig. 2a—e. 
Bexoprera Levesauet; D’ Orb. et Fér. 1839. Céphal. Acetab. Seiches, tab. 20, figs. 10-12. 
— - Pictet. 1845. Traité élément. de Paleont. vol. ii, p. 316. 
B. testa oblongo-elongatd, arcuatd, subtus carinatd, lateribus depressd, sub-excavatd ; 
antice cylindrico-angustatd : rostro obtuso, striato: appendicibus lateralibus parvis, 
linearibus. 
Shell elongated, arched: the sheath straight and nearly cylindrical; the ventral 
paries thickened, and laterally much compressed, so that, instead of the flat square- 
shaped, bifurcating ridge which distinguishes the preceding species, it presents along 
the middle of the sheath, beneath the siphuncular line, a somewhat acute angular keel, 
which is continued on the upper part of the rostrum, and the sides of which are a 
little depressed. The rostrum itself is larger, and is transversely more compressed, 
and less inflected towards the ventral aspect, than that of B. Belemnitoidea. 
M. d'Orbigny describes the species as destitute of lateral expansions ; but, in the 
figures given by him, there are unquestionable indications of those appendages, very 
slightly developed it is true, yet still representing the wing-shaped expansions which 
characterise the genus. In one of the two English specimens, the only two with which 
I am acquainted, and for the use of which I am indebted to Mr. Wetherell, the lateral 
expansions are broken away, but their existence is evidenced by a deep suture on each 
side where they were inserted into the shell. The other specimen unfortunately is 
broken off just above the juncture of the sheath with the rostrum, at the precise part 
