THE PAST AND PRESENT OF CUTTLE-FISHES. 757 



stalks in the ten-armed cuttle-fishes, but are unstalked in the eight- 

 armed species. Each sucker (Fig. 2) exhibits all the structures inci- 

 dental to an apparatus adapted to secure effective and instantaneous 

 adhesion to any surface. It consists of a horny or 

 cartilaginous cup (a), within which are muscular 

 fibers converging toward its center, where they ^/S 1 "^^ c 



form a well-defined plug or piston (b). By the iSE8lIIva 



withdrawal of this plug a partial vacuum is pro- ^SW^W 



duced, and the suckers adhere by atmospheric 

 pressure to the surface on which they are placed. 

 The sucker is released by the projection of the 

 plug and by the consequent destruction of the 

 vacuum. The number of the suckers varies, but 

 is always considerable ; and when we reflect that 

 the array of suckers can be instantaneously ap- 

 plied, and that their hold is automatically perfect, 

 the grasp of the cephalopods is seen to be of the FlG - * suckers of the 



. . Cuttle-fish. 



most efficient kind. In some cuttle-fishes, and most 

 notably in the so-called "hooked squids " (Onychoteuthis), the pistons 

 of the suckers are developed to form powerful hooks, by means of 

 which the prey may be secured with additional facility ; and in the 

 common squids the margin of the sucker is provided with a series of 

 minute horny hooks. The " arms " themselves, it need hardly be re- 

 marked, are extremely mobile ; they are highly muscular, and can be 

 adapted with ease to the varied functions of prehension and move- 

 ment they are destined to subserve. As regards their arrangement, 

 they are arranged in four pairs a dorsal and a ventral pair, and two 

 lateral pairs ; the two elongated tentacles, when developed, being 

 situated between the third and fourth pairs of arms on the ventral or 

 lower surface. 



The alimentary tract or digestive system of the cuttle-fish race is 

 in every respect of well-developed and complete character. Lower 

 down in the molluscan series the commissariat department is subserved 

 by a very perfect digestive apparatus, including representatives of 

 most of the organs familiar enough to us in higher or vertebrate ex- 

 istence. In the cephalopods we should naturally expect the standard 

 of lower- molluscan organization to be further elaborated ; and this 

 anatomical expectation is justified by the actual details of cuttle-fish 

 structure. The mouth opens on the upper surface of the head a dis- 

 position of matters already accounted for when considering the rela- 

 tions of the cuttle-fish body to that of other mollusks. The mouth- 

 opening is usually bounded by a raised lip, and leads into a cavity 

 containing an elaborate apparatus, analogous to the jaws of higher 

 animals, and by means of which the food of these animals is triturated 

 and divided. An inspection of the masticating apparatus of a cuttle- 

 fish readily solves the question, "How are the hard shells of their 



