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February 14, 1850. 

 Sir RODERICK I. MURCHISON, Vice-President, in the Chair. 

 The following papers were read : — 



1 . " Supplementary Observations on the Structure of the Belemnite 

 and Belemnoteuthis." By Gideon Algernon Mantell, Esq., LL.D., 

 F.R.S., Vice-President of the Geological Society, &c. 



In this communication the author describes his recent investiga- 

 tions on the structure of the two genera of fossil Cephalopoda, whose 

 remains occur so abundantly in the Oxford clay of Wiltshire, 

 namel}^ the Belemnite and Belemnoteuthis, as supplementary to his 

 memoir on tiie same subject, published in the Phil. Trans. 1848. In 

 that paper evidence was adduced to show the correctness of the 

 opinion of the late Mr. Channing Pierce as to the generic distinction 

 of these two extinct forms of Cephalopoda. 



As however several eminent naturalists had expressed doubts as 

 to some of the opinions advanced by the author in his former memoir, 

 figures and descriptions are given in the present notice, of beautiful 

 and instructive specimens lately discovered in Wiltshire, and which 

 he conceives establish his previous conclusions. Dr. Mantell then 

 states as the result of his examination of several hundred examples, 

 that our knowledge of the organization of the animal of the Belem- 

 nite is at present limited to the following parts, viz. — 



1. An external Capsule or periostracum which invested the osse- 

 let or sepiostaire, and extending upwards, constituted the external 

 sheath of the receptacle. 



2. The Osselet, characterized by its fibrous radiated structure, 

 terminating distally in a solid rostrum or guard, having an alveolus, 

 or conical hollow, to receive the apical portion of the chambered 

 phragmocone ; and expanding proximally into a thin cup, which 

 became confluent with the capsule, and formed the receptacle for 

 the viscera. 



3. The Phragmocone^ or chambered, siphunculated, internal shell ; 

 the apex of which occupied the alveolus of the guard, and the upper 

 part constituted a capacious chamber, from' the basilar margin of 

 which proceeded two long, flat, testaceous processes. 



These structures comprise all that are at present known of the 

 animal to which the fossil commonly called " The Belemnite^' 

 belonged. 



Of the Belemnoteuthis^ the fossil cephalopod which Prof. Owen 

 regards as identical with the Belemnite, many examples of the bo'dy 

 with eight uncinated arms, and a pair of long tentacula, having an 

 ink-bag and pallial fins, have been discovered. The osselet of this 

 animal, like that of the Belemnite, has a fibro-radiated structure, 

 investing a conical chambered shell ; but this organ, for reasons 

 fully detailed in the memoir, the author considers could never have 

 been contained within the alveolus of a Belemnite ; the soft parts 

 of the animal of the Belemnite are therefore wholly unknown. 



Many beautiful specimens of Belemnites and Belemnoteuthis were 



