MOLLUSCA CEPHALOPODA. 



259 



The Cephalopoda have been so named from the 

 position of certain organs of progressive motion, 

 which are situated on the head, and like the ten- 

 tacula of the Polypus, surround the opening of 

 the mouth. (See Fig. 121). These feet, or arms, 



or tentacnla, if we choose so to call them, are long, 

 slender, and flexible processes, exceedingly irri- 

 table, and contractile in every part, and provided 

 with numerous muscles, which are capable of 

 moving and twisting them in all directions with 

 extraordinary quickness and precision. They 

 are thus capable of being employed as instru- 

 ments; not only of progressive motion, but also 

 of prehension. For this latter purpose they are 

 in many species peculiarly well adapted, because, 

 being perfectly flexible as well as highly muscu- 

 lar, they twine with ease round an object of any 

 shape, and grasp it ^vith prodigious force. In 

 addition to these properties they derive a re- 

 markable power of adhesion to the surfaces of 

 bodies from their being furnished with nume- 



