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 



