I \ 1 1 



projections upon tin- latier which eni.T between the tub 



the opposed 1 11:111 tic. The complexity of I 1 1 i - :i 1 1 :ieh men I I 



ii. will in- perceived, with the activity of tin- :iiiiin:il. :in<l in the 



comparatively ^lu--i>h littoral ^eiM-ra it i- not r.iiii.| :it. .-ill. 



This is found only in the dibranchiate cephalopoda, :nnl 

 amongst them only fully developed in the decapod division, /. r., 

 aniou- the pela-ic species, whose <|iiick movements require the 

 support to the body which the shell allords; neverMiele>s.il is 

 prefigured in the cartilaginous blades lodged in the l>;iek of the 

 Or!.|)o.is. :nid is inoi-e fully develo|)e(l in the single Octopod 

 i:-eiius, Cirroteuthis. which possesses the menus of more rnpid 

 motion in its l;iri:v wel> or nmbn.'llM. 



The intern;)] shell is simple, usmdly, in form, heini;- u blade or 

 pen lodged in M poueh or slit in the b;iek of the inimtlc. with :in 

 anterior, moi'e or less spi-cializcd, prolongation of its rhaehis or 

 (juill. 'Hie internal shell is either horny or chitinous and Iran-- 

 parent, as in Loliii-o, or M. sponiiy. chalky mass, as in Sepia, or 

 calcareous, as in the fossil Belemnites, or mother-of-pearl, as in 

 Spirilla : in the latter, only, takino- the spiral form of the external 

 shells of the. let ralu'aiiehiate cephalopoda. 



The feather-Shaped horny shell of the Loliiro resembles, and is 

 railed, a /"'//.and its rhaehis. prolonged in front like a quill, com- 

 pletes the resemblance. This rhaehis is on the ventral side, when 

 the pen is lodged in the mantle. The wings, or lateral projec- 

 tion--. ;ire. commonly, broader in the female than in the male 

 individuals. 



When the shell is both corneous and testaceous, as in Sepia. 

 ainon^- recent u'cncra and in several fossil forms, it, may consist 

 of a thin, horny blade, occupying the entire dorsal surface of t In- 

 mantle, with an imderlyinLr Spongy calcareous ma>s attached. In 

 Sepia we lind. always, the so-called a-rial chambers obliqucly 

 placed and not connected by a siphon, and sometimes terminated 

 by a sharp rostrum, whilst in fossil ovnera. as Be] opters, these 



chambers are arranged in a single line, or in Spimlirostra they 



ln-eome a spiral series, connected by a siph<)ii and anah>-M; 

 the ^hell of the Spirilla ; which l:itt-r i-> free in tin- mantle, without 



