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 burchelli , 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 burchelli. 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, crawshayi , 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. 
