toes, the thumb being a mere stump, which is much used for holding the nuts while they are being cracked. The tail, which is large and bushy, serves the double purpose of balancing the body whilst leaping through the air, keeping it dry by being folded over its back, and enabling the animal to keep warm when curled around it.
Squirrels are widely dispersed throughout the world, being absent alone from Australia and Madagascar. In the Palæarctic Region, which stretches from England to Japan, only one species is known, although individuals from various localities are constant to themselves, and slightly different from their neighbours. It is, however, in the Indian and Oriental region that the species reaches its maximum development, and the number of species recorded from that region is very large. Putting aside for the moment the question of species, subspecies, races, varieties, &c., and looking as far as possible at the groups as a whole, we find that they give us such abundant opportunities for the study of colour in nature, and the causes by which it is influenced, that they can but form a valuable lesson to the zoologist, whatever may be his particular line.
I will preface my remarks by saying at the outset that our knowledge on the subject is very limited, and that at present we are in the position of only recording facts, which, however, may at some future time bear considerable fruit. In the first place, there is the colour of the animals, which, in the case of our English Squirrel, may be roughly called red.[1] This colour is modified during the course of the year[2] by two moults, in spring and autumn, the change taking place in May and October. In its winter dress it is greyish brown in colour, the hairs being long and soft, the tail is of a similar colour, and the ears are also clothed with long brown hairs; in May all the body-hairs are cast, and are replaced by shorter and coarser hairs of a much redder colour, while the tufts on the ears are not replaced. The hairs of the tail are not moulted at the spring moult. This may seem to be only the natural course of things to an ornithologist, but a moment's thought will at once show us that the causes
