MOUSE, a small rodent mammal of the family Muricke, the larger members of which are called rats, hamsters, lemmings, voles (qq.v.), etc.; specifically, the house-mouse (Mus muscat/us), originally Asiatic, but universally domesticated. The family is an extremely large one, embracing some 300 well-established spe cies, and is distributed over the whole world ex cept the islands of the Pacific. A mouse is the only native mammal of Australia besides the dingo (q.v.) not a marsupial. The members of this family vary in size from some smaller than a house-mouse to the bigness of the Amer ican muskrat (q.v.); and exhibit much diversity in form, especially in respect to the limbs, which in woodland and aquatic species are usually of nearly equal size, but in those that dwell on prairies and deserts are far from it, the hind-legs there becoming immensely en larged and serving as almost the only means of safety (by leaps), while the fore-legs are of little use except as hands in holding the food. It is a characteristic of mice, as of squirrels, to lift the food to the mouth and gnaw it while the animal sits up on its haunches. The poliex (thumb) on the fore feet is a mere wart-like rudiment; but the hind feet have five full toes, and in some aquatic species these are connected by webs forming swimming feet. The skull is shapely, the nose is long, pointed, hairy, keenly sensitive to odors, and protected by remarkably long tactile hairs (whiskers) ; the eyes and ears are usually large, for these animals are mainly nocturnal in habits; and the teeth are peculiar in that the lower incisors are compressed and pointed, and the molars (usually three on each side) are rootless. The tail in nearly all rats and mice is long, always thinly haired, often naked or scaly, and in such aquatic species as the muskrat is compressed into a powerful scull ing oar. Most species burrow or make their homes in holes; a few are arboreal. The near est relatives of the group are the dormice, mole rats, jerboas and pouched rats or gophers, a list which shows that the word °mouse° and "rat" is popularly applied to many small rodents outside the Murida% This family is divisible into 10 sections —Murine, or typical Old-World mice; Hydromyinw; Phynconiyinre; Gerbillins; Otomyince; Lophiomyirue; Mi crotintr, or voles; Sigmodonttnar, or hamsters; and Neotominer.
The first sub-family contains the various rats (q.v.), the house-mouse, the delicate harvest mouse and more than 100 other species of Eu rope and Asia, which agree in having wide up per molars marked by three series of tubercles and in other distinctive peculiarities. The
house-mouse has been a denizen of men's habi tations probably ever since housekeeping began, finding there safety from many natural enemies, opportunities and materials for nest-making, and plentiful daily food. It accompanies mankind wherever he goes, and soon replaces in frontier houses the local wild mice which for a time at tempt to imitate its domestic habits. These mice are about three inches long, the tail meas uring one and one-half inches more. The gen eral color is bluish or dusky brown, but is sub ject to variation and influenced by cilmate, food and other external conditions. Albino or "white" mice, with pink eyes, are kept as pets, also black and piebald ones; and these breeds are easily maintained by selective breeding. Such pets are readily tamed and taught simple tricks. Certain individuals, known as °singing mice," make, especially at night, a pleasing whistling noise, like feeble chirpings of a ca nary-bird. The same sound has been heard from wild-mice, and is believed to result from an asthmatic condition rather than to be a normal musical utterance. The fecundity of mice is excessive. From six to ten young are produced in a litter, and this species brings forth several times in the year. In about a fortnight the young are able to shift for themselves, although born in a helpless condition. This illustrates how sometimes, under especially favorable conditions, mice may multiply far beyond normal num bers and overrun the country as a devastating plague, instances of which are mentioned under FIELD MOUSE. The two most common European types, the long-tailed brown field-mouse (M. sylvattcus) and the diminutive harvest-mouse (M. nu/lulus) are farmers' pests, destroying large quantities of grain. The harvest-mouse is one of the smallest of mammals and constructs a beautiful and elegant little nest of the blades of grass or corn, entwined round and supported by the stalks of the corn or wheat. A similar smaller species in South Africa weighs only a quarter of an ounce. These out-door species hibernate during winter and lay up an autumnal store of grain in their nests and burrows —a matter in which great diversity of habit exists elsewhere in the family.