122 CEPHALOPODA. 



resembling a parrot's beak, and consisting of two horny pieces 

 that overlap one another : eyes sessile (except in Nautilus, 

 where they are pedunculated), very large and prominent, and 

 of a complicated structure : foot divided into 8 lobes called 

 arms, which in the Dibranchiata are closely studded on the 

 inner side with cup-shaped suckers, like those of the tentacles ; 

 these arms serve for catching and retaining the prey, as well 

 as for crawling : gills internal, 2 or 4, symmetrical, pyramidal, 

 and laminar. Sexes separate. 



Shell, when present, in the Dibranchiata mostly internal 

 and supporting the back, and consisting of a cartilaginous or 

 cellular plate ; but in Argonauta it is external, and forms a 

 single nautiloid chamber ; and in Spirula it is partly external, 

 and forms a spiral of several chambers, the last of which is 

 occupied by part of the body ; in the Tetrabranchiata it is 

 invariably external, nautiloid in shape, and formed of nume- 

 rous chambers, the last of which contains the whole body. 



The Cephalopoda, including the " Squids " and 

 "Cuttlefishes^ (which are the only British kinds), are 

 the highest class of the Mollusca, having a more spe- 

 cialized organization than any other class ; and they 

 are in many respects allied to the true fishes. Their 

 history also is more ancient, the Octopus vulgaris (77-0- 

 \v7rov$) with its suckers being used as a simile in the 

 Odyssey. Aristotle seems to have been intimately 

 acquainted with all the principal kinds living in the 

 eastern archipelago of the Mediterranean, as well as 

 with their anatomy, habits, embryology, and sexual 

 conditions, including the hectocotylus, or that strange 

 terminal process of one of the arms of the male Argo- 

 nauta which is developed at the proper season, and 

 serves for propagation. This last remarkable fact was 

 not rediscovered until 1841, when Delle Chiaje, and 

 afterwards Yerany, noticed it. The inky fluid which all 

 Cephalopods emit, from fear or in order to escape detec- 

 tion, was compared to urine by the celebrated Greek 



