CEPHALOPODA. 



529 



(i) rising from the bottom of the cavity, like 

 the piston of a syringe. When the sucker is 

 applied to a surface for the purpose of adhe- 

 sion, the piston, having previously been raised, 

 so as to fill the cavity, is retracted, and a 

 vacuum produced, which may be still further 

 increased by the retraction of the plicated cen- 

 tral portion of the disc. So perfect is the me- 

 chanism for effecting this mode of adhesion, 

 that in the living Cephalopod, " while the mus- 

 cular fibres continue contracted, it is easier to 

 tear away the substance of the limb than to 

 release it from its attachments : and even in the 

 dead animal the suckers retain a considerable 

 power of adhesion."* 



Still there are circumstances in which even 

 this remarkable apparatus would be insufficient 

 to enable the Cephalopod to fulfil all the offices 

 in the economy of nature for which it was 

 created; and in those species which have to 

 contend with the agile, slippery, and mucus- 

 clad fishes, more powerful organs of prehension 

 are superadded to the suckers. 



In the Calamary the base of the piston is 

 inclosed by a horny hoop, the outer and ante- 

 rior margin of which is developed into a series 

 of sharp-pointed curved teeth. These can be 

 firmly pressed into the flesh of a struggling 

 prey by the contraction of the surrounding 

 transverse fibres ; and can be withdrawn by the 

 action of the retractor fibres of the piston. Let 

 the reader picture to himself the projecting 

 margin of the horny hoop developed into a 

 long, curved, sharp-pointed claw, and these 

 weapons clustered at the expanded terminations 

 of the tentacles, and arranged in a double alter- 

 nate series along the whole internal surface of 

 the eight muscular feet, and he will have some 

 idea of the formidable nature of the carnivo- 

 rous Onychoteuthis. 



Banks and Solander, in Cook's first voyage, 

 found the dead carcase of a gigantic species 

 of this kind floating in the sea, between 

 Cape Horn and the Polynesian Islands, in 

 latitude 30 44' S. longitude 110 33' W. 

 It was surrounded by aquatic birds, which 

 were feeding on its remains. From the parts 

 of this specimen, which are still preserved in 

 the Hunterian Collection, and which have 

 always strongly excited the attention of natu- 

 ralists, it must have measured at least six feet 

 from the end of the tail to the end of the tenta- 

 cles. The natives of the Polynesian Islands, 

 who dive for shell-fish, have a well-founded 

 dread and abhorrence of these formidable 

 Cephalopods, and one cannot feel surprised that 

 their fears should have perhaps exaggerated 

 their dimensions and destructive attributes. 



We cannot quit this part of our subject 

 without noticing a structure which adds greatly 

 to the prehensile powers of the uncinated 

 Calamaries : at the extremities of the long ten- 

 tacles, besides the uncinated acetabula, a cluster 

 of small simple unarmed suckers may be ob- 

 served at the base of the expanded part. When 

 these latter suckers are applied to one another, 



* Roget, Bridgewater Treatise, i. p. 260. See 

 also Baker, An Account of the Sea-Polypus, Phi- 

 losoph. Traus. vol. 1. p. 777. 



the tentacles are firmly locked together at that 

 part, and the united strength of both the elon- 

 gated peduncles can be applied to drag towards 

 the mouth any resisting object which has been 

 grappled by the terminal hooks. There is 

 no mechanical contrivance which surpasses 

 this structure : art has remotely imitated it in 

 the fabrication of the obstetrical forceps, in 

 which either blade can be used separately, or, 

 by the interlocking of a temporary joint, be 

 made to act in combination. (See Jig. 215, 



where d marks 



Fig. 215. thestemsofthe 



peduncles, e 

 the parts joined 

 together by the 

 mutual apposi- 

 tion of the un- 

 armed suckers, 

 f the terminal 

 expanded por- 

 tions bearing 

 the hooks.) 



The great 

 muscular coni- 

 cal basis which 

 gives origin to 

 the feet is at- 

 tached, as be- 

 fore mention- 

 ed, to the an- 

 terior part of 

 the annular 

 cephalic carti- 

 lage : it is also 

 provided with 

 distinct fasci- 

 culi of muscu- 

 lar fibres, which 

 connect it to 

 the mantle and 

 to other parts 

 of the body. 



In the Octo- 

 pus a great pro- 

 portion of these 

 fibres arise from 

 the posterior 

 part of the man- 

 tle, and, di- 

 verging as they 

 pass forwards, 

 spread over the 

 posterior and 

 lateral parts of 

 the head, rece- 

 ding at the sides 

 to leave a space 

 for the eye ; 

 they then di- 

 vide into five 

 bundles, each 

 of which again 

 subdivides into 

 two, which are 

 lastly inserted 

 into the sides 

 of the six dorsal and lateral feet. (See a, a> 

 /g.216.) 



-d I 



A rms and Tentacles of an 

 Onychoteuthis. 



