34 MECHANICAL FUNCTIONS. 



CEPHALOPODA. 



Among the mollusca, next to the acephala, in the or- 

 der of organic developement, 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. 



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 locomotion, but as those of prehension also. 



The Cuttle Fish. One of these most singular ani- 

 mals is represented by fig. 22, being one of the Sepice. 

 or Cuttle fish tribe, called Loligo, or Calamary. 



In addition to the prehensile powers of these tentacu- 

 la, by which they grasp objects with great force, by 

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

 hesion by means of suckers, in the form of tubercles 

 placed along their inner sides, as shown in the figure. 



" So great is the force" says Mr. Roget " with which 

 the tentacula 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 sub- 

 stance of the limb, than to release it from its attach- 

 ments. 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^ 

 plied to certain animals 1 Give some description of the cuttle fish. 



