PLANT-EATING MAMMALS 171 



specimen, however, is immature, and it is at present unknown 

 whether the adult is hornless or not. 



No mention of the feeding habits of Ruminants would be 

 complete without allusion to the way in which the Camel 

 (Came IMS) is adapted, as regards drink, to desert conditions. 

 The paunch here presents two swollen regions, resulting from 

 a raising of the lining into folds, so arranged as to bound some 

 800 good-sized storage-cells for water. The opening into each 

 of these can be closed by the action of a ring-muscle with which 

 it is provided. It may be noted in passing that Camels possess 

 upper front teeth, and that the manyplies is represented by a 

 simple tube. 



The Hippopotamus, among non-ruminating Artiodactyles, is 

 a voracious plant-eating form, contrasting in this respect with its 

 omnivorous allies the Pigs. Some noteworthy features of the 

 common kind (Hippopotamus amphibius) may be enumerated. 

 The formidable tusk-like incisors and canines grow continuously 

 throughout the life of the animal, and are forwardly directed, 

 the latter being kept sharp by natural wear (see vol. i, p. 108). 

 The arrangement is adapted for digging up water-plants and 

 shearing off vast quantities of all sorts of vegetation. Once 

 within the mouth the food is chewed by large cheek-teeth, the 

 broad crowns of which wear into a characteristic double-trefoil 

 pattern. The huge stomach ( 1 1 feet long) is four-pouched, and 

 the intestine may be 180 feet long. Such a digestive tube is 

 clearly suited to deal with an immense bulk of food. 



ELEPHANTS (PROBOSCIDEA) 



Elephants (see vol. i, p. 103) present a number of interesting 

 adaptations to the herbivorous habit. Prehension is here the 

 function of an immensely elongated nose or proboscis, which is a 

 sort of exaggerated edition of the Tapir's snout. The muscle of 

 which it is mainly composed is arranged in a very complicated 

 manner, enabling all sorts of elaborate curving movements to be 

 performed. A greater range of possibilities is here presented than 

 in the Giraffe, for though in that animal the long neck enables 

 leaves and shoots at a considerable height from the ground to 

 be reached, grazing on the ground is rendered more difficult, 

 and can only be effected by straddling out the long fore-legs 

 in a particularly ungraceful attitude. The trunk of the Elephant, 



