30 



MECHANICAL FUNCTIONS. 



CEPHALOPODA. 



67. Among the mollusca, next to the acephala, in the 

 order of organic development, come the cephalopoda* a 

 name which signifies head-footed, in allusion to the situa- 

 tion of the organs of locomotion, which are on the head. 



68. These parts consist of many long, flexible, muscular 

 legs, or fleshy processes, situated like the tentacula of the 

 polypi, around the opening of the mouth. These members 

 answer the double purposes of legs and arms, of feet and 

 hands, for they are not only employed as organs of loco- 

 motion, but as those of prehension also. 



69. The Cuttle Fish. One of these most singular ani- 

 mals is represented by Fig. 22, being one of the sepia, or 

 cuttle-fish tribe, called loligo, or calamary. 



Fig. 22. 



70. In addition to the prehensile powers of these ten- 

 tacula, by which they grasp objects with greater force, by 

 twining around them, they also have the power of adhe- 

 sion by means of suckers, in the form of tubercles placed 

 along their inner sides, as shown in the figure. 



71. "So great is the force," says Dr. Roget, " with 

 which the tentacular of the cuttle-fish adhere to bodies by 

 means of this apparatus, that while their muscular fibres 

 continue contracted, it is easier to tear away the substance 

 of the limb, than to release it from its attachments. Even 

 in the dead animal," he continues, " I have found that the 

 suckers retain considerable power of adhesion to any 

 smooth surface to which they may be applied." 



What is the meaning of the term cephalopoda? Why is this term ap- 

 id to wrtain animals? Gue some description of the cuttle-fish. 



