124 CATALOGUE OF CEPHALOPODA. 



Belemnosepia (pars) Buckland, Geol. et Min. i. 371. ii. 68. t. 44. f. 

 ]. 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. t. 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 Aim. Sci. Nat. 1842, t. , 

 Paleont. Franc. 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 distiuct forms being confounded in the 

 present genus Belemnites. 



Synopsis of the Sections of the Genus. 



* Without any dorsal or ventral Groove. — Acceli. 



f Lateral Lines none. — Acuarii. 

 ff Lateral Lines two on each Side — Clavati. 



** Ventral Groove distinct. — Gastrocceli D'Orb., Notosiphi- 

 tes Duval. 



f Lateral Lines none. — Canaliculati. 

 yf Lateral Lines two on each Side. — Hastati. 



3* Dorsal Groove distinct. — No tocceli D'Orb., Gastrosiphi- 

 tes Duval. 

 | Lateral Lines two on each Side. — Dilatati. 





