DIGKSTIVE SYSTEM OF FISHES. 243 



Polypterus, the Dory, the Coiyphene, the Chfetodonts, and the Cod- 

 tribe. In the Whiting the two chief lobes extend the whole length 

 of the abdomen. The liver is trilobed in the Corviua, the Clupeoid 

 and the Cyprinoid fishes : in many of the latter family it almost con- 

 ceals the convoluted intestinal canaL The broad and flat liver of the 

 Raiidaj is trilobed. The liver is much subdivided in the Sand-lance 

 and in the Tunny, in which latter fish it presents remarkable modi- 

 fications of the vascular system. * There are few well-established 

 exceptions to the general rule of the presence of a gall-bladder in 

 the class of Fishes. My dissections confirm the statement of its 

 absence in the Lump-fish by Cuvierf and Wagner. | Cuvier did not 

 detect a gall-bladder in Lates niloticus, Holocentriim Sogho, Sjihy- 

 rcBua Barracuda, Trigia Lyra, Tr. Cuculus, Corvina dentex, Gli- 

 phisodon saxatilis, Lepidopus argenteus, Labrns iurdus, Ammodijtes, 

 and Echineis remora. The gall-bladder is wanting in the Ammocete 

 and Lamprey, but exists in the Myxinoids ; it is absent in the Pristis, 

 Zygcuna, and Selache, but is present in Galeus, and others of the 

 Shark-tribe. I have studied the rich series of observations recorded 

 by Cuvier § and his able Editors || on the gall-bladder and gall- 

 ducts in fishes without obtaining a clue to the law of the develop- 

 ment of the special receptacle of the biliary secretion in fishes. The 

 pouch in which the aggregated hepatic ducts terminate in the 

 Selache maxima may compensate for the absence of the gall-bladder 

 in that Shark ; these ducts are enclosed in a broad fiat band of dense 

 cellular tissue {fig. 65, L), which passes obliquely down in front of 

 the stomach as far as the duodenum, when each of the ducts opens 

 by a separate oblique orifice into a common cavity (ib. m.) of an oval 

 form, communicating with the duodenum by a single opening. 



Tlie gall-bladder is usually situated toAvards the fore-part of the 

 liver, and attached to the right lobe when this exists (as in fig. 

 61. m). In some Cyprinoids and Rays, and in the Sturgeon, it is 

 imbedded in the substance of tlie liver. In many Chaitodonts and 

 Salmonoids, in the Sword-fish, in the Eel and the Murtena, it hangs 

 freely at some distance from the liver. I found the gall-bladder three 

 inches from the liver in a Lophius of two feet in length. The size of 

 the gall-bladder varies in different fishes : it is very small in most Rays ; 

 in Osseous Fishes it usually bears a direct relation to that of the liver 

 itself. It is pyriform in the Lophius, Mullet, Sea-perch (Sebastes), 

 Pike, Sturgeon, Planirostra, and most other Fishes : it is subspherical 

 in the Gray-shark {Ga/ct(s), and in the AVolf-fish : it is like a long- 

 necked flask in Polypterus ; is bent like a retort in Xiphias, and is 



* Eschiicht, CI. f XIII. t. iv. p. 551. \ xnii. 



§ XXIII. passim. || xiii. t. iv. pt. ii. p. 559 — 569. 



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