764 MAMMALIA. 
Sub-Order PROBOSCIDEA 
The sub-order is now represented by two species of 
elephant (Z/ephas). They occupy a somewhat isolated 
position, though distinctly Ungulates. As regards skull, 
proboscis, and teeth, they are highly specialised, but their 
limbs are of a generalised type. 
The elephants are confined to the Ethiopian and Oriental 
regions. They feed on leaves, young branches, and herbage, 
By means of the mobile proboscis they gather their food, 
and they drink by filling the proboscis and then ejecting the 
water into the mouth. 
The proboscis is a muscular extension of the nose, and 
bears the nostrils at its tip. The skin is strong, and the 
hair somewhat scanty. 
In the limbs, radius and ulna, tibia and fibula, are 
quite distinct ; the radius and ulna are fixed in a crossed 
position; owing to the length of the humerus, and yet 
more of the femur, and the vertical position in which 
they are carried, elbow and knee are lower than usual, 
and the gait is peculiar; the carpal and tarsal bones have 
flat surfaces; the feet are broad, and bear five hoofed 
toes embedded in a common integument. There are no 
clavicles. 
The skull is very large, being adapted to support the 
proboscis and tusks, and to afford a broad insertion for 
the large muscles. In most of the bones there is during 
growth an extraordinary development of air-spaces, which 
communicate with the nasal passages. The supra-occipital 
is very large ; the nasal bones are very short ; the zygomatic 
arch is slender and straight, its anterior part is formed by 
the maxilla, for the elephant differs from the typical 
Ungulates in the fact that the jugal merely forms the 
median part of the zygoma, and does not extend on to the 
face. The lachrymal is also small, and placed almost 
entirely within the orbit (cf. the Rabbit). 
The dentition is unique. The two upper incisors or 
tusks are mainly composed of solid ivory; the enamel is 
restricted to the apex, and soon wears off. As the tusks 
grow, their roots sink through the premaxillaz into the 
maxilla, There are mo canines nor premolars. The 
