mi PHYLUM MOLLUSCA 783 



opening of the right sperm-duct of the male is situated on a 

 cylindrical prominence — the penis (pen.) — placed close to the 

 middle line. In the female the nidamental glands are, as in Sepia, 

 conspicuous objects when the mantle-cavity is exposed ; but they 

 are mainly situated on its posterior instead of its anterior wall. 



Enteric Canal. — The mouth is surrounded by a peristomial 

 membrane beset with numerous papilla 1 . There is a pair of 

 jaws (Fig. 681, yaw) of similar shape to those of Sepia, but much 

 more powerful, and calcified towards the tips. The buccal mass 

 is a large rounded body with thick muscular walls. On the floor 

 of the contained cavity is a large and prominent odontophore 

 (odotit.), with long and pointed, curved teeth. In front of the 

 odontophore is a large bilobed soft prominence, the tongue (tong.). 

 Behind the odontophore, between it and the opening of the 

 oesophagus, are one large median and two lateral tongue-like pro- 

 minences beset with papillae ; on the inner surface of the latter 

 are the apertures of a pair of salivary glands. 



The oesophagus (as.) becomes dilated aborally into a very 

 spacious crop (cr.) for the storage of the food, which consists of 

 small prawn-like Crustaceans and small Fishes broken up by the 

 jawsandradula. This opens into a rounded stomach (stom) having 

 very much the appearance of the gizzard-like caecum of Sepia. 

 The intestine (int.), shortly after it leaves the stomach, develops 

 a rounded caecum (coec.) with complexly folded walls, into which 

 the ducts of the digestive gland or " liver" open. The intestine 

 does not pass straight to the anus as in Sepia, but first bends 

 round in a short coil. The ink-sac and duct of Sepia are 

 not represented. There is a very large digestive gland divided 

 into four main portions or lobes, each of which is made up of 

 a number of lobules. The ducts ("bile-ducts," b. du.), opening 

 as above mentioned into the caecum, have a series of small 

 diverticula which may represent the pancreatic appendages of 

 Sepia. 



The coelome consists of the pericardium and the gonocosle — the 

 cavity in which the gonad is enclosed : these communicate with 

 one another by three apertures. The pericardium contains the 

 ventricle, the four auricles, and parts of the renal glandular 

 appendages. It communicates with the exterior by the viscero- 

 pericardial apertures. 



Heart and Vascular System. — The vascular system consists of 

 the heart, the arteries and veins, and certain large spaces constituting 

 the haemoccele. The latter consists of three chief parts — the peri- 

 stomial, peri-oesophageal and peri-hepatic haemocoeles, the first sur- 

 rounding the buccal mass, the second the oesophagus, and the third 

 the liver. 



The ventricle (Figs. 681 and 683, vent.) is a bilobed, transversely 

 placed, muscular sac, very similar to that of Sepia. On either side 



3 D 2 



