18 OCTOPODA. 



Order OCTOPODA. 



Body naked. Head separate, with eight fleshy arms, 

 furnished with sessile cups, without any horny ring ; eves 

 fixed in the skin. Gills two ; siphuncle entire. Foot 

 none. 



No internal medial dorsal shell. 



In this order of Octopods there are only eight arms, 

 the two elongated tentacular arms being wanting ; their 

 bodies are rounder than the Decapods, and they are not 

 so amply provided with fins. The only genus furnished 

 with a shell is the Argonaut, the shell, however, has only 

 been found on females, and may possibly serve merely as 

 a receptacle for the ova ; when there is an internal shell 

 it is quite rudimentary. 



Fam. OOTOPODID^. 



Arms subulate. Mantle supported by fleshy bands. 

 No cephalic aquiferous apertures. 



In this family, consisting of five genera, the arms are 

 similar, elongated, and united at the base by a web ; the 

 shell, according to Professor Owen, is represented by two 

 short styles encysted in the substance of the mantle. In 

 their habits they are chiefly littoral, feeding along the 

 coasts of the temperate and tropical zones : they escape 

 detection by varying their tints according to the nature 

 of the ground over which they pass, and elude the vigi- 

 lance of their enemies by discolouring the water with an 

 inky cloud, which they pour out of their ink-bag when 

 pursued. 



