THE ONYCHOTEUTI11S. 



163 



cavity, is retracted so as to produce a vacuum ; and such is the 



muscular force of the animal that it 



is easier to tear away the substance of 



the limb than to release it from its 



attachments. 



In the decapods, which are not con- 

 fined to the coasts like the eight-footed 

 poulps, but have to contend with the 

 agile, slippery, and mucus-clad fishes, 

 we find the disks provided with a sharp 

 hook fixed in the centre, and to add 

 to their efficacy they are mounted on 

 stalks movable in every direction. Let 

 the reader picture to himself these 

 weapons, clustered at the expanded 

 terminations of the tentacles (/), and 

 arranged in a double alternate series 

 along the whole internal surface of 

 the eight muscular feet (c), and he 

 will have some idea of the formidable 

 nature of the Onychoteuthis. 

 Besides the hooked acetabula, a cluster 

 of small simple unarmed suckers may 

 be observed at the base of the expanded 

 part. These add greatly to the animal's 

 prehensile powers, for when they are 

 applied to one another (e), the tenta- 

 cles are firmly locked together at that 

 point, and the united strength of both 

 the elongated peduncles can be applied 

 to drag towards the mouth any resist- 

 ing object which has been grappled by 

 the terminal hooks. There is no me- 

 chanical contrivance which surpasses 

 this admirable structure. 



The size of the arms and the ar- 

 rangement of the suckers differ con- 

 siderably in the various species. In 

 the octopods, which generally lead a more sedentary creeping life 

 and clinging to stones seize the passing prey, the arms, in ac- 



M2 



Arms and Tentacles of an 

 Onychoteuthis. 



