xvii] THE COMPARISON OF RELATED FORMS 1091 



problem of how best to fit the horizontal leg-stripes and the vertical 

 body-stripes together. There is only one way. A pair of body- 

 stripes diverge apart and the upper leg-stripes fit in between-, 

 becoming at the same time chevron-shaped so as to adapt them- 

 selves to the space they have come to occupy. The stripes of the 

 forelegs, and their manner of fitting on to the body-stripes, vary 

 very little in the several species or varieties. 



A third series of stripes ascends the hindlegs, in a fashion iden- 

 tical to begin with for all, but open to modification where these 

 leg-stripes spread over the hauncljes; for here there hiay be great 



Fig. 553. Zebra's head, to shew how the body-stripes 

 extend to the face. From A. Rzasnicki. 



differences in the extent to which the leg-stripes compete with and 

 interfere with, or (so to speak) encroach upon, the stripes of the 

 body. Tne typical Equus zebra is easily recognised by the so-called 

 "gridiron" on its rump; this is a dorsal continuation of the body- 

 stripes, extending to the tail, but sharply cut off on either side by 

 the stripes ascending from the leg (Fig. 554, C). In Burchell's zebra 

 the hindleg-stripes encroach still farther on the body, and even 

 reach up to the rump, so that the "■ gridiron is entirely cut away*. 



* Ward's zebra and Grant's zebra are varieties of Equus zebra, the former with 

 a very strong "gridiron," the latter with a mere vestige of the same: which is as 

 much as to say that the leg-stripes encroach little in the one, and much in the 

 other, on the hindmost body-stripes. Chapman's zebra is a form of E. Burchelli, 

 with well-striped legs and faint intermediate striping. Cf. W. Ridgeway, on The 

 differentiation of the three species of Zebra, P.Z.S. 1909, pp. 547-563; also {int. al) 

 Adolf Rzasnicki, Zebry, Warsaw, 1931. 



