L)1GEST1VK SYSTEM OF FISHES. 237 



are there carded and comminuted, and again swallowed, to be re- 

 duced to chymous pulp by the solvent power of the secretions and 

 by the continuous grinding pressure of the spiral movements of the 

 gastric parietes. It is liighly probable, thei'efore, that the shortness 

 and width of the esophagus, the masticatory mechanism at its com • 

 mencement, and its direct terminal continuation with the cardiac 

 portion of the stomach, relate to the combination of an act analogous 

 to rumination, with the ordinary pi-ocesses of digestion, in all Fislies 

 possessing those concatenated and peculiar structures. For it will 

 be seen that the Fishes, as, for example, the Sturgeon, the Paddle-fish, 

 the Dog-fish, and the Selache, whose oesophagus is best organised 

 to prevent regurgitation from the stomach, are devoid of the pharyn- 

 geal jaws and teeth. 



Fishes disgorge the shells and other indigestible parts of their 

 food : and it is known to practised anglers that Fishes, when hooked 

 or netted, often empty their stomach by an instinctive act of fear, or 

 to facilitate escape by lightening their load.* 



The intestinal canal is shorter in Fishes generally than in the higher 

 Vertebrata : in the Dermopteri, Plagiostomes, Holocephali, Sturionida3 

 (see the Paddle-fish,^^. 61./ to *), the Lepidosiren (xxxui. pi. 25. Jigs. 

 1 and 2.), the Flying-fish, the Loach, the Gar-pike, the Wolf-fish, the 

 Salmon, the Herring, and the apodal fishes, it is shorter than the body 

 itself : in some of the above-cited examples, the intestine extends in a 

 straight line from the pylorus to the anus {Jig. 46. i) ; in most fishes 

 it presents two or three folds ; it is sinuous in the Sword-fish ; concen- 

 trically and subspirally wound in the Mullet, in which the convolu- 

 tions are numerous and form a triangular mass ; and it is in this 

 fucivoi'ous fish, in the Chajtodonts, and the Carp-tribe, that the intes- 

 tinal canal attains its greatest lengtli in the present class. 



With a few exceptions, of which the Dermoptei'i and the Lepido- 

 siren are examples, the intestines are divided into ' small' and ' large.' 

 The beginning of the small intestine, to which is arbitrarily given 

 the name of 'duodenum' {Jig. 61. i) is usually wider than the rest 

 of that division of the canal: it receives the ducts of the liver and 

 pancreas, the latter accessory organ presenting, in most Osseous 

 Fishes, the elementary form of simple cajca {fig. 63. k\ which are 

 usually termed, from their communication with, or development from, 

 the commencement of the small intestine, ' appendices pylorica3.' The 

 termination of the small intestine is commonly marked by a circular 



* A netted Snlmon is generally found with an empty stomach ; whence it has been 

 suijposod, nolwitlistandhig its extraoriliiiary arr<iy of teetli, that its staple food con- 

 sisted of such auimalcules as are alone, under those circumstances, discoverable in the 

 gastric mucus. 



