822 



CEPHALOPODA. 



apposition {Nautilus) or are actually united (Cuttle-fishes), in such 

 a manner as to form a muscular tube, known as the " funnel." 

 The funnel (fig. 736, /) is placed on the lower surface of the 

 body, with its anterior extremity projecting beyond the mantle, 



while it opens behind into the 

 pallial chamber. It serves for 

 the elimination of the water 

 which has been used in respi- 

 ration, and the out-going cur- 

 rents also carry away with them 

 the excretions of the kidneys 

 and of the ink-sac, together 

 with the faeces. By the con- 

 tractions of the mantle, the 

 water contained in the pallial 

 sac can also be driven through 

 the funnel in a succession of 

 jets, driving the animal back- 

 wards through the water. 



The mouth in the Cephalo- 

 pods conducts into a powerful 

 buccal cavity or pharynx (fig. 

 736,^) containing two power- 

 ful mandibles, working verti- 

 cally, resembling the beak of 

 a parrot in shape, and either 

 horny (as in the Cuttle-fishes), 

 or partially calcified (as in 

 Nautilus). There is also a 

 toothed tongue or " radula." 

 The intestine is short, and the 

 anal opening is placed at the 

 base of the funnel. The 

 Cuttle-fishes possess a special 

 glandular organ, the " ink- 

 bag " (fig. 736, i), which 

 secretes an inky fluid, which 

 the animal can discharge into 

 the water, so as to facilitate 

 its escape when menaced or 

 pursued. The duct of the 

 ink-sac opens, along with the intestine, at the base of the funnel ; 

 but in the Pearly Nautilus and its extinct allies the ink-gland is 

 entirely absent. 



A well-developed heart is present in the Cephalopods, and the 



Fig. 736. — Diagram of the structure of a Cuttle- 

 fish, ph, Pharynx, with the horny mandibles ; 

 sa, Salivary glands ; ce, CEsophagus ; s, Stomach ; 

 c, Gastric caecum ; in, Intestine ; /, Liver ; n, 

 Oesophageal nerve-collar ; g, One of the gills, 

 with the branchial heart at its base ; i, Ink-bag, 

 its duct opening along with the intestine and 

 generative duct at the base of the funnel ; ov, 

 Ovary ; d, Oviduct (the nidamental and accessory 

 glands are omitted) ; f, Funnel, p, Pen, lying in 

 the mantle dorsally. 



