269 



ON THE ARMS OF THE BELEMNITE. 

 By G. C. Crick, F.G.S., etc. 



Bead 8th March, 1907. 

 PLATE XXIII. 



In a paper communicated to this Society,' in discussing the relationships 

 of the fossil which Professor James Buckman named Belemnoteuthis 

 Montefiorei, the present writer incidentally referred to the number of 

 the arms of the Belemnite, and stated that it seemed "fairly safe to 

 conclude that those Belemnites, of which any remains of the arms had 

 been obtained, had only six uncinate^ arms." - The conclusion is so 

 important that it seems desirable to fully set forth the evidence on 

 which such a statement was made. This is attempted in the present 

 paper. 



The statement that the Belemnite possessed only six uncinated arms 

 is not new, although it seems to have been generally overlooked, for 

 Professor Huxley,^ writing in 1864 on the structure of the Belemnitidse, 

 says (p. 16): "I have not been able to make out more than six or 

 seven arms in any specimen, nor has any exhibited traces of elongated 

 tentacles, though the shortness of the arms which have been preserved 

 would lead one to suspect their existence." 



In England remains of Cephalopoda with uncinated arms have been 

 recorded from both Lower Liassic and Oxfordian rocks. Whenever at 

 all well preserved, each arm is seen to have borne a double row of 

 booklets, but the character of the booklets of the Liassic forms is very 

 different from that of the booklets of the Oxfordian forms. In all 

 cases the booklets seem to have been placed on the inner surface of 

 the arms, with their proximal ends towards the base of each arm ; the 

 distal end of each booklet is pointed and turned inwards. In the 

 Oxfordian forms the proximal end, or that which was attached to 

 the arm, is also pointed, whilst in the Liassic examples this part of 

 each booklet is thickened. The booklets of the Oxfordian specimens 

 have been well figured by Professor Owen,* who referred the species 

 possessing them to the genus Belemnites, but they have long since 



1 Proc. Malac. Soc, vol. v, pt. 1 (April, 1902), pp. 13-16, pi. i. 



2 This fact is alluded to by Professor G. B. Howes in his address as President of the 



Section of Zoology at the meeting of the British Association in 1902 (Report, 

 p. 631) as follows: — "In palaeontology, history records the fact that in 1864 

 Huxley observed that the genus Belemnites appears to have borne but six free 

 arms, a startling discovery which lay dormant till the present year." 



' T. H. Huxley: Mem. Geol. Surv. United Kingdom, Figures and Descriptions 

 illustrative of British Organic Remains, Mon. ii, "On the Structure of the 

 Belemnitidse," etc., 1864. 



* Phil. Trans., 1844, pis. iii, v, vi. 



