DEGLUTITION. 159 



dently intended to prevent the return of the food 

 into the mouth. Grazing quadrupeds, which, while 

 they eat, carry their heads close to the ground, have 

 a long oesophagus, with thick muscular coats, ca- 

 pable of exerting considerable power in propelling 

 the food in the direction of the stomach, which is 

 contrary to that of gravity. 



§ 7. Receptacles for j-etamino' Food. 



Provision is often made for the retention of the 

 undigested food in reservoirs, situated in different 

 parts of the mouth, or the oesophagus ; instead of 

 its being immediately introduced into the stomach. 

 These reservoirs are generally employed for laying 

 in stores of provisions for future consumption. 

 Many quadrupeds have cheek pouches for this 

 purpose : this is the case with several species of 

 Monkeys and Baboons ; and also with the 3Ius 

 cricetus, or Hamster. The 3Ius hursarius, or Canada 

 rat, has enormous cheek pouches, which, when 

 distended with food, even exceed the bulk of the 

 head. Small cheek pouches exist in that singular 

 animal, the Ornithorhynchus. The Sciuri(s pal- 

 marum, or Palm squirrel, is also provided with a 

 pouch for laying in a store of provisions. A re- 

 markable dilatation in the lower part of the mouth 

 and throat, answering a similar purpose, takes 

 place in the Pelican ; a bird which displays great 

 dexterity in tossing about the fish with which it 

 has loaded this bag, till it has brought it into the 

 proper position for being swallowed. The Whale 

 has also a receptacle of enormous size, extending 



