WHITE OR SQUARE-MOUTHED RHINOCEROS 663 
the sun was at another angle, or when the sky-effect was 
different. A comparison of the skins shows that there is 
a very real difference of color, the hook-lipped rhino being 
of such a dark gray that it can legitimately be called black, 
while the square-mouthed species is of a smoky gray, a 
gray which can readily look whitish in certain lights. The 
ordinary name is by no means so much of a misnomer as 
we had supposed. The square-mouthed animal is totally 
unlike the hook-lipped one, so much so that it undoubtedly 
ought to go in a different genus; the two are at least as 
distinct as the moose and the wapiti. According to our 
observations the square-mouthed rhino averaged consider¬ 
ably larger than the hook-lipped, but there was overlapping 
between the smaller individuals of the first and the excep¬ 
tionally big ones of the second; and the same was true of 
the horns, which averaged longer in the square-mouthed. 
African big-game animals offer many puzzling examples 
of discontinuous distribution, and none more so than the 
square-mouthed rhinoceros. It was first known from the 
region between the Orange and the Zambesi, where it 
abounded, but was practically exterminated in the late 
eighties, so that now only a few individuals are left in a 
game reserve. North of the Zambesi it is not found until 
the great Nyanza Lakes are passed. Indeed, until Major 
Gibbons discovered it on the left bank of the upper White 
Nile, it was believed to be confined to South Africa. Exam¬ 
ination of the series of specimens we brought home shows 
that there is only the smallest distinction, hardly of sub¬ 
specific value, between these two widely separated groups 
of white rhinos. According to what Mr. Selous writes it 
appears probable that all the rhinos west of the Nile belong 
