350 



MANUAL OF ZOOLOGY. 



two branchiae only, and comprises the Cuttle-fishes, Squids, 

 and the Paper Nautilus. The latter is distinguished by the 

 presence of four gills, and, though abundantly represented in 

 past time, has no other living representative than the Pearly 

 Nautilus alone. 



CHAPTER LI. 

 DIVISIONS OF THE CEPHALOPODA. 



ORDER I. DIBRANCHIATA. The members of this order of the 

 Cephalopoda are characterised as being swimming animals, al- 

 most invariably naked, with never more than eight or ten arms, 



which are always pro- 

 vided with suckers. There 

 are two branchiae, which 

 are furnished with bran- 

 chial hearts ; an ink-sac is 

 always present; the funnel 

 is a complete tube, and the 

 shell is internal, or, if ex- 

 ternal, is not chambered. 

 The Cuttle-fishes are 

 rapacious and active ani- 

 mals, swimming freely by 

 means of the jet of water 

 expelled from the funnel. 

 The arms constitute pow- 

 erful offensive weapons, 

 being excessively tenacious 

 in their hold, and being 

 sometimes provided with 

 a sharp claw in the centre 

 of each sucker. They are 

 mostly nocturnal or cre- 

 puscular animals, and they 

 Fig -, I4 6 >;T A r ? otte %i nr "' f h - e " Paper 1 S a - u ' . sometimes attain to a ^reat 



tilus, female. 1 he animal is represented in . ,, T i 



its shell, but the webbed dorsal arms are se- ' S1ZC. 1 hey may DC divided 



embrace^ " 1 ' 1116 SheU ' Whi h ^ rdinarUy into tWO Sections, Octopodd 



and Decapoda, according as 



they have simply eight arms, or eight arms and two additional 

 " tentacles." 



