Page:The Zoologist, 4th series, vol 2 (1898).djvu/490

458 adaptation. One of my friends who is not usually accustomed to pay special attention to such animals, told me that he had been much surprised to notice that on the two banks of a brook on which the soil was of different colours, the Grasshoppers were in each case exceedingly like the ground in colour. Without doubt these were Acridium germanicum or A. cærulescens,—the latter species appears to show the same adaptation." Canon Tristram in his North African travels met with an area of the limestone conglomerate with earlier pebbles, in which a fine white flint, not previously observed, predominated. Here, to use his own words, "we found only two living things through the whole day—a curious white Scorpion, and a Desert Lark (Annomanes regulus, Bp.)." In Kamschatka, where the ground is so long covered with snow, Mr. Guillemard, in comparing the Great and Lesser Spotted Woodpeckers, the Capercailzie, and the Marsh Tit, with the forms found in Europe, remarks: "In all these the differences consist for the most part in the greater predominance of white in the plumage, and this tendency to albidism is noticeable, as I have already mentioned, in other animals besides the birds; the Dogs and Horses likewise showing it in a marked degree." Sometimes the effect may be very sudden and of an artificial character. It is difficult to explain the process as described by C.J. Andersson in South Africa:—"In the course of the first day's journey, we traversed an immense hollow, called Etosha, covered with saline incrustations, and having wooded and well-defined borders. Such places are in Africa designated 'salt-pans.' The surface consisted of a soft greenish yellow