DR. MANTELL ON THE BELEMNITE. 
395 
nifying power of eight diameters in Plate XXIX. fig. 6. In this section are clearly 
seen the outer integument or periostricum (a), the radiated structure of the osselet 
(b), and the shell of the phragmocone (c). Among the numerous Belemnites I have 
examined, not the slightest trace of an inh-hag or its contents, the sepia, could be de- 
tected. 
Belemnoteuthis. — Some uncompressed examples of the distal end of the phrag- 
mocones of this Cephalopod have lately been discovered, which must dispel any 
remaining doubts as to the generic distinction, first established by the late Mr. Chan- 
NiNG Pearce in 1842, being based on natural characters. 
The specimen figured, Plate XXIX. fig. 7, appears to me to afford conclusive evi- 
dence on the points in dispute. By a reference to my former paper, it will be seen that 
the longitudinal ridges, which are always present on the distal end of the phragmocone 
of the Belemnoteuthis, are regarded by those observers who contend that the latter 
belong to Belemnites, as plaits, or folds, originating from fracture and lateral com- 
pression. In the fossil before us these ridges are entire and well-defined ; two are 
situated on the ventral and one on the dorsal region. Fig. 7“ is a transverse section, 
enlarged four diameters, in which are shown the form of the ridges and the radiated 
structure of the solid part of the phragmocone : I scarcely need observe, that in the 
true Belemnite the cone is chambered to the extreme apex. These characters will 
remind the palseontologist of the very analogous organization of the Beloptera of the 
tertiary strata, alluded to in my former memoir*. In fact it is now proved that the 
Belemnoteuthis (as was originally suggested by Mr. Channing Pearce and Mr. Cun- 
nington) possessed an osselet of a radiated structure containing a chambered siphun- 
culated cone, but without an extended rostrum or guard ; thus forming an interesting 
transition to the Belemnite, from which it is generically distinct-f-. From the facts 
before us, our knowledge of the organization of the genus Belemnites comprises the 
following structures : — 
1. The investing periostricum or capsule, which enveloped the osselet, and extend- 
ing upwards, constituted the external parietes of the receptacle. 
2. The Osselet, characterized by its radiated structure, composed of trihedral pris- 
matic fibres, which terminated distally in a solid rostrum having an alveolus or conical 
hollow to receive the lower portion of the chambered phragmocone, and proximally 
in a thin cup-like expansion, which became confluent with the capsule, and formed 
the receptacle for the viscera. 
3. The Phragmocone, or conical siphunculated chambered internal shell, the apex 
of which occupied the alveolus of the rostrum, and the upper part expanded into a 
capacious chamber, from the basilar margin of which proceeded two elongated testa- 
ceous processes. 
* Philosophical Transactions, 1848, p. 176. 
t The Conoteuthis Dupiniams of M. D’Oebigny, from the Upper Neocomian strata of the Department 
d’Aube, appears, so far as can be determined by mere description, to approach very closely to the Belemnoteu- 
this. It is stated to have a long slender osselet, terminated by a chambered cone, but without a guard or 
rostrum. 
3 E 2 
