612 LECTURE XXIV. 



hand-net to catch an Octopus that was floating within sight, with its 

 long and flexible arms entwined round a fish which it was tearing 

 to pieces with its sharp hawk's bill ; the Cephalopod allowed the 

 net to approach within a short distance of it, before it relinquished 

 its prey, when in an instant it relaxed its thousand suckers, ex- 

 ploded its inky ammunition, and rapidly retreated under cover of the 

 cloud which it had occasioned, by quick and vigorous strokes of its 

 circular web. 



The Cephalopods which frequent the more open seas, and which 

 have to contend with more agile and powerful fishes, have still more 

 complicated organs of prehension. In the Calamary the base of the 

 piston is enclosed in a horny hoop with a dentated margin. In the 

 Onychoteuthis the margin is produced into a long, curved, sharp- 

 pointed claw. These formidable weapons are sometimes clustei'ed at 

 the expanded terminations of the tentacles, and in a few species are 

 arranged in a double alternate series along the whole internal surface 

 of the eight ordinary arms, as they were in the extinct Belemnite. 



The peripheral fold of membrane of the sucker can be expanded 

 beyond the piston, so as to act on a hard surface like the unarmed 

 sucker of the Octopus : but, so applied to the mucous surface of a 

 fish, it might glide off : the better to hold on such slippery ground, 

 the horny dentacles and hooks are superadded ; the latter, in Onycho- 

 teuthis, are retractile, as in the cat's paw ; and it is interesting to find 

 this earliest appearance of the retractile claw illustrating numerically 

 the law of vegetative repetition. 



In connection with the uncinated acetabula at the extremities of 

 the long tentacula of the Onychoteuthis, may be observed a cluster 

 of small simple unarmed suckers at the base of the expanded end. 

 When these parts in each tentacle are applied to one another, they 

 become locked together, and the united strength of both the peduncles 

 is thereby more effectually brought to bear upon any resisting object 

 which may have been grappled by the terminal hooks. This is a very 

 striking mechanical contrivance: human 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.* 



In the diminished number, increased size, and progressive complica- 

 tion of the cephalic muscular appendages, and in their final modifica- 

 tion for combining with one another to produce a determinate action, 

 we trace the common order which regulates the development of other 



of " Zoological Recreations," and other delightful contrihutions to our common 

 favourite science. 



♦ CCCCIV. vol. i. p. 529. 



