HERBIVOROUS MAMMALS 75 



their food are of interest. The majority use their 

 teeth, which, in such cases, are chisel-shaped in front. 

 All the ruminants press the grass between their tongue 

 and upper toothless gums. The horse grasps with his 

 lips, the tapir with the longer flexible snout which, 

 in the elephant, is drawn out into a trunk of the utmost 

 sensitiveness and strength, serving not only to reach 

 up to lofty boughs for the juicier leaves, but also 

 to overturn trees whose summits are out of reach. 

 Squirrels and monkeys, on the contrary, use their hands 

 for conveying food to the mouth. 



The need for thoroughly chewing such food has 

 entailed great modifications of the teeth and face. 

 The long face of the horse is due to the lodgment 

 of many grinders. The complex form and large 

 size of these teeth enable them to act as a mill, 

 those of the upper jaw fitting into the hollows and 

 bosses of the lower teeth ; whereas, since the upper and 

 lower j aws of the ruminants are not equally wide, the 

 teeth act intermittently on one side first and then on 

 the other. To equip themselves for encountering dusty 

 herbage, the Herbivora have developed an elaborate 

 arrangement for separating dust and pollen from the 

 air which enters the nose in order to gain the lungs. 

 The bones that form the framework and support of 

 the nasal passages are converted into labyrinths, so 

 that the air whirls round on its way to the lungs, 

 and in so doing deposits the heavier particles on the 

 sticky walls, as a ' separator ' divides the cream from 

 the milk. The dust, pollen, and spores are then carried 



