TIIK SK1X. 



typical eighl arms. In this animal only, the body is contained 

 ltlll "' : "" 1 Protected by, an external shell, which compensates 

 the loss of offensive and locomotive power possessed l, x it, 

 moiv highly oro-;mi/e<l nllie>. 



Behind th, ; u-n.,, II,, ,i,-,l, ( ,r which i,,,v (-onsli,,,!, its ,,,,,, 



ll;lt "''.>< Portion of bhe head is situated whirl, is usually ,lis- 



tmctively so designated ; its dorsal aspect exhibits on either side 



n "' lu ' :i<] m *y be joined to the body by a more or less 



Constricted ^, or is frequently sessile upon the latter, withoul 



intervening constriction. The body, or mantle, is dorsally more 



continuous with the head, but ventrally forms '.-, sack 



anteriorly open, and from which emerges the funnel or siphon 



(which may also be regarded as a modification of a portion of the 



foot of the gasteropoda). The sack or body is, in a small portion 



Soctopodand in tee decapod species, expanded into p6stero- 



''1 membranes, possessing the power of undulatory motion 



'""I which may be considered as the equivalent t>f fins, in func- 



tion. t hoiioh not in M 



Tin' Skin. 



The epithelium in the dibranchiate <-<>plmlopo,js is ,-, 



of (fcsklike or rounded grain.like cells; they are cylindrical in 

 II"' N.ntilus. Cn.lcM- M lis !i( , s fl tllil , a broos layer, 'which again 



tll!lt containing ih,- chromatophores. The skin of the 

 cephalopod, particularly its dorsal surface, is covered with 

 apparently minute specks of a dark reddish color, which are in 

 reality, the pigment cells or chromatophores (PI \-> rs 9). these 

 :1IV each provided with radiating muscles, : by which, at the will 

 " n "< 1 animal, the little sacte are greatly dilated, and the color 

 becomes intensified. The rapid chameleon-like changes of color 

 |M1(M!ll!ir 1<> tllr ''I'l'--'l'>l"'<l.-i --.M.ono n.ollus,,,. ; tl v thus pro.hn-,,! - 

 whilst M,, accompanying opal-like and silvery appearance <-x' 

 I " hl1( " 1 b y the cuttle-6shes, is due to a thin layer underlying the 

 pigment layer, ...! reflecting through ii. I,, n,,. tentacles of 

 Nautilus are found epithelial pigment cells, which, according to 

 Rumphius,are osed simih.Hy to the chromatophores. 



outer Bkin,in many of the genera, is furnished with con 



tubercular elevations or /.,.,/.,. w , li( .,, .,, paiged wh 



