Page:The Zoologist, 4th series, vol 2 (1898).djvu/423

Rh mammals, and the skin of all the Snakes and Lizards, is of one uniform isabelline or sand colour." Brehm writes:—"The birds, the reptiles, and even the insects show the same stamp, though form and colouring may vary greatly. When any other colour besides sandy yellow becomes prominent, if hair, feather, or scale be marked with black or white, ashy grey or brown, red or blue, such decorations occur only in places where they are not noticeable when looked at from above or from the side." But he also remarks:—"The fact that almost all the desert animals agree in colouring with their surroundings explains why the traveller who is not an experienced observer often sees, at first at least, but little of the animal life." This appears to better illustrate the survival of an original assimilative colouration than to afford an example of the strict definition of what is meant as "protective resemblance," which affords an extraneous means of survival under an increased competition of life. Mr. Beddard, discussing the effects of temperature and moisture on the colours of animals, considers it "at least possible that the tawny colours of desert animals, which have been so often brought forward as an instance of adaptation to the hues of their environment, may be due to a similar cause." Mr. Quelch, writing on the Birds