24 



POPULAR CONCHOLOGY. 



sist of a cavity which lies on each side near the brain ; 

 those of smell have not yet been settled with certainty. 



The above simple description of the Cephalopoda is 

 derived from Dr. Philippi's work ; but, as he gives no infor- 

 mation concerning the extraordinary apparatus with which 

 the arms are beset, a concise account shall be given from 

 Dr. Roget's Bridgewater Treatise. " These feet or arms, or 

 tentacula, are long, slender, and flexible processes, exceed- 

 ingly irritable, and contractile in every part, and provided 

 with numerous muscles, which are caj)able of moving and 

 twisting them in all directions with extraordinary quick- 

 ness and precision. They are thus capable of being em- 

 ployed as instruments, not only of progressive motion, but 

 also of prehension. For this latter purpose, they are in 

 many species peculiarly well adapted, because, being per- 

 fectly flexible as well as highly muscular, they twine with 

 ease round an object of any shape, and grasp it with pro- 

 digious force. In addition to these properties, they derive 

 a remarkable power of adhesion to the surfaces of bodies, 

 from their being furnished with numerous suckers* all 

 along their inner sides. ... So great is the force 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 substance 

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

 in the dead animal I have found that the suckers retain 

 considerable power of adhesion to any smooth surface to 

 which they may be applied." 



It will be seen in the following descriptions of the 

 genera composing this order, that these arms differ greatly, 

 but all are covered with formidable suckers. 



The inky fluid, which some of these creatures have the 



* These act almost like cupping glasses. 



