Page:The Zoologist, 4th series, vol 2 (1898).djvu/492

460 beauty." This cannot be taken as an instance of pure but only partial assimilative colouration, but is sufficient to prove that colour may be largely derived from the mineral constituents of the earth's surface, and in this way can scarcely be altogether ascribed to the action of "natural selection." These bright wing feathers may have subsequently served the purpose of "recognition markings"?, but seem certainly not derived directly for that purpose.

A better example may be found in the Red Hartebeest (Alcelaphus cokei). Sir H.H. Johnston narrates of this species: "Being a deep red-brown in colour, and standing one by one stock-still at the approach of the caravan, it was really most difficult and puzzling sometimes to know which was Hartebeest and which was ant-hill; for the long grass hiding the Antelope's legs left merely a red-humped mass, which, until it moved, might well be the mound of red earth constructed by the white termites. The unconscious mimicry was rendered the more ludicrously exact sometimes by the sharply-pointed flag-like leaves of a kind of squill—a liliaceous plant—which frequently crowned the summit of the ant-hill or grew at its base, thus suggesting the horns of an Antelope, rather with the head erect, or browsing low down. The assimilation cannot have been fancied on my part, for it deceived even the sharp eyes of my men; and again and again a Hartebeest would start into motion at twenty yards distance, and gallop off, while I was patiently stalking an ant-hill, and crawling on my stomach through thorns and aloes, only to find the supposed Antelope an irregular mass of red clay." This would seem to be almost an instance of acquired or active mimicry on the part of this animal. Here the whole question to be considered is what was the original home of this Red Hartebeest? Is it a creature of these red-earthed plains, the character of which is so prominently shown in these gigantic ant-hills?