124 
CATALOGUE OF CEPHALOPODA. 
Belemnosepia (pars) Buchland , Geol. et Min. i. 371- ii. 68. t. 44. f. 
1. 7, 12. 
Dr. Buckland gives a theoretical figure of the animal of this 
genus, which appears most consistent with the specimens I have 
examined (see Geol. and Mineralogy with Nat . Theology , ii. 70. t. 
44. f. 1. 1836); and figures a Belemnites, with the upper part of 
the shell preserved (1. c. ii. t. 4. f. 7, 8, 9, 10, 11, 12. 1836). 
Dr. Mantell (Phil. Trans. 1848, t. 15. f. 2. 3.) has figured a 
specimen which appears to have an elongated process on each side, 
like the processes on the side of the mouth of certain Ammonites ; 
but, on examining the specimen, I am very doubtful if this ap- 
pearance does not arise from an accidental fracture of the upper 
part of the conical sheath. 
M. D’Orbigny describes the shell of this genus as horny, en- 
larged in front into a spathuliform dorsal plate, contracted behind, 
with a conical cavity furnished with concave septa, having a 
siphon on the ventral edge traversing all the cells, and coated 
externally with a shelly beak. The theoretical form of the bone 
is represented by M. D’Orbigny in Ann. Sci. Nat. 1842, t. , 
Paleont. Franq. Ter . Juras. t. 2. f. 1, 2. t. 3. f. 1, 2, 3. t. 4. f. 1., 
Moll. Viv. et Fos. i. t. 35, 36. The authority for this dorsal ex- 
pansion appears to rest on certain lines seen on the outside of the 
cone of Belemnites giganteus var. aalensis , which, he thinks, 
resemble the grooves found on the dorsal surface of the bone of 
the cuttle-fish, Sepia or Loligo , and hence he believes they have 
a similar enlarged dorsal plate. This may be the case with some 
species, though, I believe, no specimens have been found to establish 
this theory, and the external surface of the conical part of other 
Belemnites shows no indication of any such grooves ; but this may 
arise from two or more distinct forms being confounded in the 
present genus Belemnites. 
Synopsis of the Sections of the Genus. 
* Without any dorsal or ventral Groove. — Acoeli. 
f Lateral Lines none. — Acuarii. 
ff Lateral Lines two on each Side. — Clavati. 
** Ventral Groove distinct. — Gastrocceli D 1 Orb., Notosiphi- 
tes Duval. 
f Lateral Lines none. — Canaliculati. 
Lateral Lines two on each Side. — Hastati. 
3* Dorsal Groove distinct. — Notocoeli D'Orb., Gastrosiphi- 
tes Duval. 
f Lateral Lines two on each Side. — Dilatati. 
