Ilurses, ZebraSy and TujArs. 4 1 5 



marks over the quarters break up iuto spots. In another 

 race, Grey's quagj^a {E. qungga f/rei/i), there are no very 

 definite inarkini^s over the hinJ-qnarter.s and posterior area 

 of the tlanksj owin^j; apparently to the toning down of the 

 dark marks and the deepening of the pale marks to u nearly 

 uniform brown ; the marks on the head and neck, however, 

 retain respectively their normal widtli, the dark marks never- 

 theless being deep brown and the pale marks creamy bruwn. 

 In yet another form, JJanielTs quagga {E. q. cianiel/i), of 

 which there are extant three coloured plates drawn by 

 different artists from different living models, the extension of 

 the light marks, which are chestnut in hue, is still further 

 carried, the dark markings being represented principally by 

 narrow lines on the head, neck, and shoulders. Finally, in 

 Lorenz's quagga, as already stated, the dark markings on 

 the head, neck, and fore-parts have encroached upon the light 

 marks, reducing them to pale narrow streaks *. 



Thus the quaggas supply evidence of a progressive evolu- 

 tion of the black and white zebroid pattern towards, though 

 never quite achieving, uniformity of colour of a brown or 

 chestnut hue, Tliis approximation to uniformity has been 

 brought about by four distinct processes ; — (1) by the 

 lightening of the dark marks and the darkening of the li"-lit 

 marks to practically the same tint ; {2) by the lightening of 

 the dark marks and their extension across the intervenino- 

 pale marks ; (3) by the dark-^ning of the light marks and 

 their extension across the intervening dark marks ; (4) by 

 the fading away of the daik marks, especially after reduction 

 in length and width has taken place. 



Thus there appear to me to be very good reasons for 

 thinking that Jolinston's view of the coloration of the Equid« 

 is correct, namely, that they are descended from dark-coloured 

 animals patterned with white spots, running into longitudinal 

 lines originally, and at a late stage in evulution becomiii"- 

 arranged in transverse bars over the neck and body. It is 

 this view of the question which, in my opinion, gives special 

 interest to the coloration of dapple-grey horses; for if, as it is 

 obvious to suggest, the white spots of these horses represent 

 phylogenetically the white spots of a tapiroid |)rogenitor, we 

 see in this dappled pattern a stage in the evolution of equine 

 coloration antecedent to the vertically banded zebroid [)attern 

 hitherto regarded as the most primitive pattern extant in the 

 Equidae. 



• I'ocock, Aun. & Mag. Nat. Hist. (7) .\iv. pp. 313-328 (l!X)4). 



