A6 BELEMNITID&. 
A. In many Belemnites the extension of the conotheca seems 
to run out in one simple broad plate, as in B. hastatus, from 
Solenhofen (ii, 22). 
B. In Belemnites Puzosianus, d’Orbigny, the pro-ostracum is 
very thin, and apparently horny or imperfectly calcified in the 
dorsal region, supported laterally by two long, narrow, parallel, 
calcareous plates (B. Puzosianus from the Oxford clay, ii, 20). 
Professor Huxley considers this difference between the pro- 
ostraca of generic importance. 
C. The third kind of pro-ostracum is exhibited by Orthoceras 
elongata, De la Beche, the type of the genus Xiphoteuthis, 
Huxley. It is calcareous, and is composed of concentric lamelle, 
each of which consists of fibres disposed perpendicularly to the 
plane of the lamella; the phragmocone is very long and narrow, 
and the guard cylindroidal. 
Professor Huxley suspects that a thoroughly well-preserved 
specimen of Belemnoteuthis will some day demonstrate the exist- 
ence of a fourth kind of pro-ostracum among the Belemnitide. 
“The Acanthoteuthes of Munster, so far as they are known 
only by hooks and impressions of soft parts, may have been 
either Belemnites, or Belemnoteuthis, or Plesioteuthis, or may 
have belonged to the genus Celceno.”—HUuxXLEy. 
The genus Belopeltis, Voltz, was founded on the pro-ostraca 
of Belemnites. 
The genus Actinocamax, Miller, was founded on the guards 
of Belemnites and Belemnitella, the upper parts of which had 
decayed, and thus presented no alveolar ¢ cavity.— WooDWARD. 
BELEMNITES, Lamarck. 
EHtym.—Belemnon, a dart. 
Syn.—Diploconus, Zittel, 1868 Actinocamax, Voltz, 1840. 
Gastrosiphites, Notosiphites and Pseudobelus, Duval. 
Distr.—l00sp., fossil only. B. excentricus, Keferst. (xxviii, 72). 
Animal, arms and tentacles with two rows of horny hooks. 
Shell, phragmocone horny and slightly nacreous, with a minute 
globular initial chamber; two nacreous bands on its dorsal side, 
and produced beyond its rim into sword-shaped processes, 
represent the rostrum, which is fibrous, cylindrical, thickened 
behind, thin in front where it invests the phragmocone. 
These animals, supposed to have been gregarious, from the 
number of their remains found in certain localities, were very 
numerous in species, over 100 having been described from the 
liassie and chalk formations of Europe, from the chalk of South- 
ern India, from the Jurassic of the Himalayas, ete. 
The phragmocone is very delicate, and its preservation is 
usually due to the infiltration of calcareous spar into its cham- 
bers. M. d’Orbigny supposes that the variation of the propor- 
