In some places in the London district a light grey Squirrel may be seen, and thought to be a colour variation of our native species. It is really an American visitor, distinct in colour and without tufts to the ears. Some years ago the caged specimens in the Zoological Gardens, Regent's Park, had become so numerous that some of them were given their liberty. Their numbers increased among the trees of the Gardens, and they overflowed into the Park, where they became so familiar as to accept food from the hands of the delighted children. Gradually, some of them developed exploring tendencies and made their way to the wooded grounds of suburban residences. British naturalists of a not-distant future will probably have to include two species of Squirrels in their lists. * * * * * The pretty Chipmunk (_Tamias striatus_, Linn.), or Chipping Squirrel, one of the Ground Squirrels, is another American species that has become acclimatised in the London area. It lacks the long tufted ears of our Squirrel, the tail is shorter, and there are pouches inside the cheeks. Its general appearance is strikingly different from the Squirrel, for though its ground colour is red-brown, the eye is set in a white band divided into two stripes by a black line. A black stripe runs down the middle of the back, and in addition there is a white stripe bordered by black above and below along each side. It feeds on nuts, beech-mast, grain, roots, and insects; migrating from place to place as local food-supplies become scanty. It stores up food for the winter like the Squirrel, carrying it to its caches by means of the cheek-pouches. Though capable of climbing, and occasionally seen ascending lofty trees, it is much more at home on the ground. It burrows a retreat in the ground, if no suitable stump is available for excavation. When startled it utters a cry of "chip-per-r-r." *Dormouse* (_Muscardinus avellanarius_, Linn.). The non-scientific observer of our native mammals satisfied himself long ago that the pretty Dormouse was a miniature kind of Squirrel, and he was helped to this conclusion by the general resemblance in colouring, the form of the head, the prominent black eyes, large ears, and thickly furred long tail; as well as by its arboreal habitat and its habit of sitting up on its haunches and holding a nut or other food in its forepaws. But the classifying naturalist has to look below the surface to discover a sound basis for his work. Superficial resemblances are often due to similarity of habit and habitat; and in this case the internal structure of the Dormouse shows that it has closer affinity with the Mice than with the Squirrels, though really distinct from both. [Illustration: _Pl. 54A._ _G 82._ Seeking for thistle-seeds. *Harvest Mice.*] [Illustration: _Pl. 54B._ _G 82._ Fighting for a wheat-ear. *Harvest Mice.*] [Illustration: _Pl. 55._ _G 83._ *Dormouse.* Muscardinus avellanarius.]