COMMON ZEBRA OR BONTE-QUAGGA 677 



typical Burchell zebra than the latter is from its more north- 

 ern fully striped races. There is a continuous progressive 

 change in coloration from the immediate vicinity of the 

 Cape or southern point of Africa, which was the habitat of 

 the extinct quagga, to typical burcheili, inhabiting the Orange 

 River district, and on through other striped forms in the 

 Transvaal to the fully striped races of southern Rhodesia or 

 Matabeleland. The typical Burchell zebra had only the 

 body striped, the legs being uniform whitish and the hind 

 quarters but weakly striped. The few specimens of the typi- 

 cal quagga which are now preserved in museums show con- 

 siderable variation in the extent of the striping, some in this 

 regard being striped on the hind quarters almost as distinctly 

 as true burcheili. The change from a partially striped animal 

 to a fully striped one takes place in the southern part of 

 the range of the species, or that portion south of the Zam- 

 besi River. North of the Zambesi River no additional 

 stripes or greater intensity of striping occurs, the races north 

 of this point showing only slight differences in body size or 

 color tone. Curiously enough, the most fully striped of all 

 the races, crazvshayi, inhabits the middle region of the 

 Zambesi, north of which races occur having a slightly 

 less number of stripes but no less distinctly striped. We 

 thus have in this zebra practically the whole range of its 

 color scheme exhibited in the southern third of its range, 

 while the northern two thirds show almost no variation. 

 What the real significance of this break in the progressive 

 color change is really due to is quite problematical. Two 

 theories suggest themselves: one that it is a climatic affair, 

 the country from the Zambesi River southward being in 

 the temperate zone and consequently showing a gradual 

 range of temperature which coincides with the gradual 

 color change, the country north of the Zambesi River 

 being tropical and of uniform climate; the other that there 

 is an important time element involved — South Africa having 

 long been the home of this particular species, the color 

 differences have come about slowly in that region, but the 

 zebra's extension northward to beyond the equator is of 

 such recent date that there has not elapsed time sufficient 

 for important color changes to take place such as are found 

 in the south. 



