CEPHALOl-ODA. 



There were at least three kinds of pro-ostracum in the 

 family BeUmnitidce. 



A. In many Belemnites the extension of the conotheca seems 

 to run out in one simple broad plate, Fig. 3, as in B. Jiastatiis 

 from Solenhofen. 



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. Fig. 4, as in B. Puzosianus from the Oxford 

 clay. Professor Huxley considers this difference between the 

 pro-ostraca of generic importance. 



0. The third kind of joro-ostracum is exhibited by Orthocera 

 elongafa, De la Beche, the type of the genus XipJioteuthis, 

 Huxley ; it is calcareous, and is composed of concentric lamellae, 

 each of which consists of fibres disposed perpendicularly to the 

 plane of the lamella ; the phragmocone is yery long and narrow, 

 and the guard cylindroidal. 



Professor Huxley suspects that a thoroughly well-preserved 

 specimen oi Belemnoteuthis vnll some day demonstrate the exist- 

 ence of a fourth kind of pro-ostracum among the Belemnitidce. 



The genera in the family are : — 1, Belemnites ; 2, Belemnitella ; 

 3, Xiphoteuthis ; 4:, Belemnoteutliis ; 5, PJesioteutJiis ; 6, CeJoeno ; 

 ^i , Beloptera ; 8, Belem7iosis ; 9, Conoteuthis; a.n6. ? Uelicerus. 



' ' The A antJwteuthes of Munster, so far as they are known 

 only by hooks and impressions of soft parts, may have been 

 either Belemnites, or BelemnoteutJiis, or Plesioteuthes, or may have 

 belonged to the genus Celceno.'' (Huxley.) 



The genus Belopeltis, Yoltz, was founded on the pro-ostraca 

 of Belemnites, species of which were unknown. 



The genus Adinocamax, Miller, was founded on the guard 

 of Belemnites and Belemnitella, the upper parts of which had 

 decayed, and thus presented no alveolar cavity. 



Oedee, II. — Tetrabeajtchiata. 



Family I. — Nautilid^ 

 (including Family II. — Oethoceeatid^). 



Division a. — Aie-chambees confined to one paet of the 



SHELL. 



AscocEEAS, Barrande, 184fi.* 

 Etymology, asTcos, a leathern bottle, and ceras, 



• At p. 185 Jlr. Woodward refers to M. Barrande's second volume of tlie " Cephalo 

 poda of Bohemia." The Ascoras, Glossoceras, and Aphragmites are here described. 



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