RUMINANT STOMACHS. 113 



placed by horny plates, which among the "Whales constitute the 

 whalebone ; and in another instance, again, the muzzle is pro- 

 longed into a very broad horny beak, flat, and furnished at the 

 side with transverse plates ; thus showing the greatest resem- 

 blance to the beak of the Duck, and causing the animal in 

 which it exists to receive the name of Ornithorhyncus, or Duck- 

 billed Platypus. 



98. The conformation of the stomach varies much in the 

 class Mammalia ; and from these differences, physiological pecu- 

 liarities of great importance sometimes result. In general, this 

 organ is simple, as in Man, and the Monkey ; but sometimes it 

 is composed of a numerous series of distinct sacs ; and in this 

 case it generally happens that the food, after having remained 

 some time in the first cavity of the stomach, returns into the 

 mouth, there to undergo a more complete mastication, before 

 passing into the other portions of the digestive tube. This 

 phenomenon is known under the name of rumination. The 

 number of the stomachs of the animals which ruminate (the Ox 

 and Sheep, for example) is four. The first, which is the largest 



CEsophagus 



Intestine 



Pylorus. 4th Stom. 2d Stom. 1st Stom. 

 FIG. 64. STOMACHS OF THE SHEEP. 



of all, is named the paunch. Its internal surface is covered with 

 papillae, and is lined by a layer of the epidermis (Fig. 65). It 

 occupies a large part of the abdomen, particularly on the left 

 side. The second stomach, called the honeycomb^ is small, and 



