ELEPHANTS, HORSES, AND CAMELS 



167 



the elephants' proboscis, or trunk, serves the same purpose and the 

 short neck permits an efficient arrangement of structures for the 

 support of the massive head. The proboscis, composed of the 

 elongated nose and upper lip, is a powerful yet delicate prehensile 

 organ. Because of its relative lightness and flexibility it is superior 

 to the jaws for handling objects, and with the head and neck 

 formed as they are becomes an exceedingly strong and efficient 



Fig. 92.— Skull of Indian elephant, in longitudinal section. B, brain cavity; 

 i, incisor or tusk; m 3-5, the third to fifth molars. (From Lull, after Owen.) 



organ. In contrast the elongation of the neck in other animals to 

 compensate length of limb is of limited use. 



The Skull. In the elephant the skull is much shorter and higher 

 than in most mammals (Fig. 92). The change in form is accom- 

 plished by the thickening of the l)ones, whose lightness is preserved 

 by the formation of large enclosed spaces. The skull of an animal 

 acts as a lever of which the occipital condyles are the fulcrum, the 

 longitudinal axis the work arm, and the vertical height above the 

 condyles the power arm. In most animals the power arm is rela- 

 tively short, but in the high skull of the elephant it is much longer 

 and the leverage availal)le for the support of the heavy head and 



