82 TELEGONY AND REVERSION. 



a general plan in their marking. I consider the Somali 

 zebra (Fig. 21) the most primitive of all the zebras. This 

 conclusion has been arrived at mainly from a compara- 

 tive study of the markings of zebras. I have examined a 

 number of skins from Somaliland (one of which was a 

 well-preserved and quite complete foetal skin), numerous 

 Burchell's zebra skins, several skins of the mountain 

 zebra, and the Amsterdam, Leyden, London, and Edin- 

 burgh quaggas. 



The chief difficulty in dealing with zebras is to find 

 possible points of comparison in the marking of the dif- 

 ferent species and varieties. In all the zebras there is, 

 however, one very distinctive stripe, viz. the stripe which 

 typically extends downwards from the withers to bifurcate 

 somewhere above the level of the shoulder-joint ; one 

 division proceeding forwards across the shoulder-joint, the 

 other backwards behind the elbow.* This characteristic 

 stripe I shall speak of as the shoulder stripe (Figs. 17, 18, 

 and 23, S.S.). Occupying the triangular space formed by 

 the two limbs of the shoulder stripe and the transverse 

 band at the base of the forearm, we find in the Somali 

 zebrat some ten narrow arches (the humeral stripes) (Fig. 

 24, H.S.), the upper ones pointed, the lower ones rounded. 

 In Matopo (Fig. 23) only portions of three humeral stripes 

 can be made out, but a Burchell's zebra filly (Fig. 25) 

 from the Transvaal had at least seven. Between the 

 shoulder stripe and the occipital crest there are in Matopo 

 twelve stripes continuous with black bands in the mane 

 (Fig. 23). In the Transvaal filly there are twelve stripes 

 on the right side and ten on the left, but as there is a 

 "shadow" or indistinct stripe (Fig. 25) running down 



* In Matopo neither of tlie divisions of the shoulder stripe reach the 

 ventral band ; this band usually begins at the junction of the two stripes 

 lying immediately iu front of the shoulder stripes. Mr. Prazak, I think 

 rightly, looks upon the shoulder stripe even when consisting of a single 

 band as made up of two stripes (' Wild Horses of Africa '). 



■j- By the Somali zebra I invariably mean the Somaliland variety of 

 Grevy's zebra, not the typical Grevy's zebra {E. greoyi, Oust.) of Shoa. 



