CEPHALOPODS. 



455 



of the expanded part. When these latter suckers are applied to one 

 another, the tentacles are firmly locked together at that part, and the 

 united strength of both the elongated peduncles can be applied to 

 drag towards the mouth any resisting object which has been grappled 

 by the terminal hooks. There is no mechanical contrivance which 

 surpasses this structure ; art has remotely imitated it in the fabrica- 

 tion of the obstetrical forceps, in which either blade can be used 

 separately, or, by the interlocking of a temporary blade, be made to 

 act in combination." Cyc. of Anat. 



The third Family, Belemnitidse, contains Belemnitella and Belem- 

 nites, and other genera of less importance ; they are all now extinct, 

 although once numerous as species. 



The cuttles, Sepia (Fig. 315), have the 

 body fleshy and depressed, continued into a 

 sac, and bordered on all its length on both 

 sides with a wing or narrow fin, the larger 

 short and flat, broader than it is long, with 

 two large eyes, covered by an expansion of 

 the skin, which becomes transparent over a 

 surface equal to the diameter of the iris, 

 and furnished with inferior contractile eye- 

 lids. 



This head is surmounted by ten tenta- 

 cular arms or feet, eight of which are short 

 and conical, and two long- and slender, ter- 

 minating in a sort of spatula. These arms Fig ' 315 ' Sepia mcinalls t^ 1 "^ 

 are all armed with suckers, and are perfectly retractile. They sur- 

 round a mouth armed with two horny jaws not unlike the beak of a 

 parrot. 



The skin of the cuttle-fish presents in one vast hollow, occupying all 

 the extent of the back, a great calcareous part, the form and structure 

 of which is quite characteristic of this genus. It is known as the 

 cuttle-bone (Fig. 316). This bone is used for many purposes; 

 among others, it is used in a powdered state as a dentifrice. It is 

 sometimes suspended in the cage with captive birds, that they may 

 whet their beaks on it, and collect phosphate of lime for the formation 

 and repair of their bones. The osselet is oval or oblong, some pro- 

 vided with a slightly salient point. The .upper part is surrounded 



