THE ALLIES OF THE SQUIRREL: MAMMALIA 417 



forming a complex organ of several compartments. The food 

 is taken into the first two of these divisions, the reticulum or 

 honeycomb bag, and the rumen or paunch, where it remains 

 till the animal has finished grazing and has leisure for its 

 digestion. The food is then raised to the mouth in a some- 

 what softened condition and is there ground between the 

 molar teeth and moistened with saliva, after which it is again 

 swallowed, this time into the psalterium, or manyplies, so 

 called from the numerous folds in its lining membrane. The 

 food slowly filters through the 

 manyplies into the true digestive 

 stomach, or abomasum. This habit 

 of chewing the cud has suggested 

 the name of 

 ruminants (Lat. 

 rumen, throat) 

 for these ungu- 

 lates. 



Though zoolo- 

 gists do not feel 

 certain as to the 

 ancestry of the 

 domestic horse 

 (E'quus cabal'lus), a recently discovered animal (Equus 

 przewal'skii, Fig. 223) of the sandy deserts of Central Asia 

 may be its progenitor. The interesting story of the geological 

 development of the horse is told farther on (p. 428). 



Of the Proboscidea the elephants alone require mention. 

 There are two existing species, the Asiatic (El'ephas in'di- 

 cus) and the African elephant (Elephas africa'nus). The latter 

 can be distinguished from the former by its very large ears. 

 The Asiatic species has long been domesticated and many 

 stories are told of its intelligence. The African species 

 was used by the Romans in battle and circus games, but in 



FIG. 222. Diagram of Stomach of Ruminant. (After 



Wiedersheim) 

 (Arrows and dotted lines show the course of the food) 



