706 MAMMALIA. 



lower down on the intestine. The testes are abdominal. 

 Of the mammae, four are on the groin and two are axillary. 

 The placenta is zonary, as in the Proboscidea and Carnivora. 

 No extinct forms are known. 



Sub-Order Proboscidea. 



The sub-order is now represented by two species of 

 elephant (Elephas). 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 the face. The lachrymal is also small, 

 and placed almost entirely within the orbit (cf. the Rabbit). 



