226 MAMMALIA. 



After the pauncli comes the bonnet or cap of the stomach (c) ; 

 this receptacle is small, and its internal mucous membrane is 

 lined with folds formed by polygonal cellules. In this cap the 

 food is gradually moulded into smaU pellets, which ascend again 

 into the mouth, by means of a natural movement, and not a con- 

 vulsive or irregular one, as in other animals ; these pellets then 

 undergo a thorough mastication and salivation. Such is " chewing 

 the cud." 



When the food, thus transformed into a soft and nearly fluid 

 paste, descends again into the stomach, it goes straight into a third 

 intestine, called the omasum or leaf (d), on account of the wide 

 longitudinal folds which line the interior of it, much resembling 

 the leaves of a book. From this it at length passes into the 

 digesting stomach, or rennet-hag (e), which is the seat of the real 

 digestion, and owes its name to the fact that its irregularly folded 

 internal surface is continually moistened by the gastric juice, a 

 fluid which has, as is well kno'VSTi, the property of curdling milk. 

 After having imdergone the digestive process, the food passes 

 from the rennet-bag {e) into the intestine duodenum (/). We 

 must add that liquids pass straight into the digesting stomach 

 without staying either in the paunch or bonnet. 



Ruminants feed chiefly upon grass, both stalks and leaves, and 

 their dental system is s^DeciaHy adajDted to such circumstances. 

 There are no incisors in the upper jaw, and there is an empty 

 space between the lower incisors and the grinders, the crowns 

 of which are wide and marked with two double crescents. At 

 the time of mastication, the movement of the jaws is nearly 

 circular. 



The feet of all these animals terminate in two toes, the meta- 

 tarsal and metacarf)al bones of which are joined together in one 

 bone, called the shanJc. Sometimes, also, there exists at the 

 back of the foot two small spurs, vestiges of lateral toes. In all 

 these animals, except Camels and Llamas, the hoofs, which 

 entirely cover the last joint of the two toes on each foot, act 

 side by side on a smooth surface, and resemble one single but 

 cloven hoof. Thus the origin of the word cloven-footed. 



We must remark, in conclusion, that these animals are the only 

 Mammals which are provided with bony extensions of the frontal 

 bones ; but all the Ruminants do not possess these. 



