CLASSIFICATION OF ASSES. 419 



tween zebras and asses in general. The fact, as pointed 

 out by Professor Ewart, that the true Burchell's zebra has 

 a well-developed ist premolar (p. 49) on each side of the 

 upper jaw, may probably come under this heading. The 

 stripes, as pointed out by Messrs. Tegetmeier and Suther- 

 land {Horses, Asses, Zebras, and Mules), are not a good 

 generic distinction, because all the Equid^e are occasionally 



Fig. 447. — Tables of incisors of a 14 year-old horse (nat. size). 



more or less marked in this manner. Even in individual 

 cases of zebras, the nature of the stripes is subject, more 

 or less,'^to variation, and they are seldom uniform on both 

 sides of the body. The stripes on the neck are continued 

 through the hairs of the mane. 



Classification of Asses — Some naturalists divide 

 asses into two species, namely, the African Wild Ass, 



27* 



