70 



The tongue is broad, short, and almost destitute of papillae. The 

 salivary glands are only rudimentary, and even wanting where the 

 liver and pancreas are well developed, but the mouth is well sup- 

 plied with mucus. The short, wide infundibuliform oesophagus 

 has an external circular, and an internal longitudinal layer of mus- 

 cular fibres, and is lined with a pale, villous, longitudinally plicated 

 mucous membrane provided with numerous mucciperous follicles. 

 The large gastric cavity is sometimes long and tapering as in the 

 herring, and sometimes globular as in the lophius: its two orifices 

 are closely approximated, so that the food is retained in it for a long 

 period, hence, if we feed a tame perch till it is gorged, it will not 

 eat again for ten or fourteen days ; both orifices of the stomach are 

 sphinctorial, its mucous membrane is plicated and forms a valve at 

 the pylorus with a fringed margin, surrounded by a ring of carti- 

 lage. The intestine, in many cases, does not measure more than 

 half the length of the body, in others, however, as the sword fish, it 

 forms several convolutions, but rarely does it admit of any distinc- 

 tion into large and small. In the sturgeon, ray, and shark the anal 

 is smaller than the cardiac portion, and the reverse obtains in the 

 pleuronectes, gadi, murcenae, &c. In order to compensate for the 

 shortness of the canal and the absence of valvulse conniventes, the 

 lining membrane is peculiarly disposed, being reticulated in the 

 sturgeon, forming spiral turns in the shark and ray, and serpentine 

 folds in the eel. The rectum here as in oviparous vertebrata, ter- 

 minates in the cloaca through which are discharged feces, urine, 

 semen, and ova. On either side of the anus there is an oblique 

 valvular opening, admitting of free egress, but prohibiting any 

 thing from without, and the air-sac, or rudimentary lung commu- 

 nicates by a membranous tube with the oesophagus, stomach, or 

 upper portion of the intestine. 



The large elongated liver is of a soft texture, light colour, and 

 divided into many lobes, it is provided with arterial and portal cir- 

 culation, and generally with a large gall-bladder as in other pre- 

 daceous vertebrata. Several long hepatic ducts join the cystic, and 

 many short ones run at once into the fundus of the gall-bladder, 

 and the short but wide choledochus either opens separately or in 

 common with one or more of the pancreatic ducts into the upper 

 portion of the intestine. The spleen is small, of various forms, 

 attached to the side of the stomach, generally simple, but lobulated 

 in the shark and sturgeon, as in some of the cetacea, and in the 

 lamprey, which has neither pancreas nor gall-bladder, it is wholly 

 absent, as in the invertebrata. The pancreas which is wanting in 

 the centriscus, presents every stage of development, from one or 

 two simple follicles as in the lophius, choetodon, (fee, up to a large, 

 compact, reniform mass, enveloped in a muscular tunic, as in the 

 sturgeon and xiphas. The large pancreatic follicles are connected 

 by loose cellular tissue, and admit the digested food info their in- 

 terior, like the biliary tubes of some mollusca. The peritoneum 

 lines the walls of the abdomen, and surrounds the viscera in the same 



