.STOMACHS OF MAMMALIA. 193 



cavities, each having probably a separate office 

 assigned to it, though concurring in one general 

 effect. A gradation in this respect may be 

 traced through a long line of quadrupeds, such 

 as the Hog, the Peccariyilie Porcupiuey(Fig/SOii), 

 and the Hippopotamus, where we find the number 

 of separate pouches for digestion amounting to 

 four or five. Next to these we may rank the 

 very irregular stomach of the Kanguroo, (Fig. 

 309) composed of a multitude of cells, in which 

 the food probably goes through several prepa- 

 ratory processes ; and still greater complication 

 is exhibited by the stomachs of the Cetacea, as, 

 for example, in that of the Porpus (Fig. 310). 

 As the fishes upon which this animal feeds are 

 swallowed whole, and have large sharp bones, 

 which would injure any surface not defended by 

 cuticle, receptacles are provided, in which they 

 may be softened and dissolved, and even con- 

 verted into nourishment by themselves, and 

 without interfering with the digestion of the soft 

 parts. The narrow communications between 

 these several stomachs of the Cetacea are pro- 

 bably intended to ensure the thorough solution 

 of their contents, by preventing the exit of all 

 such portions as have not perfectly undergone 

 this process. 



Supernumerary cavities of this kind, be- 

 longing to the stomach, are more especially 

 provided in those animals which swallow food 



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