Nearly allied to the true Mice are numerous forms more restricted in their distribution, which have been formed into distinct genera. Thus _Pelomys fallax_, in which the incisors are grooved, the tail short, and the first and fifth toes of all the feet shorter than the three middle ones, is peculiar to Mozambique; _Acanthomys_, in which the fur is mixed with flattened spines, is an African genus; whilst _Echinothrix_, which has a somewhat similar coat, is Australian. Madagascar possesses two peculiar genera, _Nesomys_ and _Brachytarsomys_, the former having some relation to the American Murinæ, the latter remarkable for the shortness of the hind feet; and in Australia, besides the genus already mentioned, and one or two species of true _Mus_, we find the genus _Hapalotis_ represented by about thirteen exclusively Australian species. These animals have the hind limbs rather long, the ears large, and the tail long and hairy, terminating in a tuft. The molar teeth also exhibit a peculiar pattern; The best known species is the WHITE-FOOTED HAPALOTE (_Hapalotis albipes_), an animal about the size of the Brown Rat, of a smoky brown colour, with the belly and the feet white. It inhabits New South Wales, especially in the mountainous parts. The animals of this genus were formerly regarded as allied to the South American Chinchillas and Viscachas. The American Murines all belong to a group to which the name of Sigmodontes has been given, because their molar teeth, which in the young state have two tubercles in each transverse row (instead of three, which is the usual number in the preceding forms), when ground down by use, show some S-like patterns in the enamel folds in place of transverse ridges. The greater number of the species belong to the genus _Hesperomys_ (Western Mouse), which is represented in both divisions of the American continent, and has been divided by authors into several sub-genera. The WHITE-FOOTED, or DEER MOUSE (_Hesperomys leucopus_) is perhaps the best known of all the species, and its varieties, or rather local permanent races, are distributed all over the continent of North America. The fur shows various brownish or greyish tints above; and the lower surface, with the feet up to the wrist and ankle, is snow-white. What Dr. Coues gives as the normal colour of typical specimens is a rich fawn, with a darker streak along the back: but he says that this is shown by not more than one example in six. The tail is generally white beneath. The length of the head and body is about three inches; the tail varies considerably in length. The White-footed Mouse is nocturnal in its habits, and feeds to a great extent upon corn, of which, with acorns and other nuts, it lays up stores for winter use. It lives a good deal upon trees, taking up its abode in the deserted nest of a Squirrel or of some small bird. When it constructs its own nest the little fabric is placed in a bush at from