The Encyclopedia Americana (1920)/Mouse

MOUSE, a small rodent mammal of the family Muridæ, the larger members of which are called rats, hamsters, lemmings, voles (qq.v.), etc.; specifically, the house-mouse (Mus musculus), originally Asiatic, but universally domesticated. The family is an extremely large one, embracing some 300 well-established species, and is distributed over the whole world except 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 American 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 enlarged 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 pollex (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 sculling oar. Most species burrow or make their homes in holes; a few are arboreal. The nearest relatives of the group are the dormice, mole-rats, jerboas and pouched rats or gophers, a list which shows that the word &ldquo;mouse&rdquo; and &ldquo;rat&rdquo; is popularly applied to many small rodents outside the Muridæ. This family is divisible into 10 sections &mdash; Murinæ, or typical Old-World mice; Hydromyinæ; Phyncomyinæ; Gerbillinæ; Otomyinæ; Dendromyinæ; Lophiomyinæ; Microtinæ, or voles; Sigmodontinæ, or hamsters; and Neotominæ.

The first sub-family contains the various rats (q.v.), the house-mouse, the delicate harvest-mouse and more than 100 other species of Europe and Asia, which agree in having wide upper molars marked by three series of tubercles and in other distinctive peculiarities. The house-mouse has been a denizen of men's habitations 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 attempt to imitate its domestic habits. These mice are about three inches long, the tail measuring one and one-half inches more. The general color is bluish or dusky brown, but is subject to variation and influenced by climate, food and other external conditions. Albino or &ldquo;white&rdquo; 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 &ldquo;singing mice,&rdquo; make, especially at night, a pleasing whistling noise, like feeble chirpings of a canary-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 numbers and overrun the country as a devastating plague, instances of which are mentioned under . The two most common European types, the iong-tailed brown field-mouse (M. sylvaticus) and the diminutive harvest-mouse (M. minutus) 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 &mdash; a matter in which great diversity of habit exists elsewhere in the family.

American native mice are all of one or the other of the remaining sub-families, or else do not belong to the Muridæ at all. The short-tailed meadow-mice (see ), the neotomas (see ), lemmings (q.v.), and their allies are elsewhere described. The most of our smaller mice belong to the sub-family Sigmodontinæ, characterized prominently by having cheek-pouches, and represented in the Old World by the hamsters. Five genera and about 75 so-called species have been catalogued, but probably further study will greatly reduce the number. Onychomys is a rather short-tailed, fossorial genus of the plains region and northern Mexico. Sigmodon is another genus of Florida and the Southwest, taking its name from the sigmoid form of the cusps of the molars; Reithrodontomys embraces several very small burrowing brown mice of the same region; and Oryzomys includes the large, handsome &ldquo;rice-field mouse&rdquo; of the Southern States (O. palustris). The fifth genus, Peromyscus, contains the most numerous and familiar of the long-tailed field-mice. These are the &ldquo;wood-mice,&rdquo; &ldquo;deer-mice&rdquo; and &ldquo;cotton-mice,&rdquo; more familiar under the old name Hesperomys, and commonly represented by the white-footed mouse (P. americanus, or H. leucopus), which occurs all over the more temperate parts of the continent. This species is somewhat larger than the house-mouse, and is yellowish brown above, darker on the back, the lower parts of the body and tail and the upper surface of the feet white; the young are dark slaty; the eyes and ears are large, and the fur long and soft. It is nocturnal in its habits, as active as a squirrel, nesting in trees, in the fields, in barns and houses, and making a dwelling resembling a covered bird's nest; it feeds principally on grain, seeds, nuts and insects; and in newly

settled districts comes into dwellings and granaries and is as mischievous as the house-mouse. Species with similar habits are a beautiful golden-haired southern one (P. aureolus); the large, dark-brown, gray-bellied cotton-mouse (P. gossypinus), very numerous in the South Atlantic States: the &ldquo;red-backed&rdquo; or Michigan mouse (P. michiganensis) of the North Central States, and several others.

Biblography.&mdash; Coues and Allen, &lsquo;Monograph of the Rodentia&rsquo; (Washington 1877); Merriam (and others), &lsquo;North American Fauna&rsquo; (Washington 1889 and subsequently); Stone and Cram, &lsquo;American Animals&rsquo; (New York 1902); Ingersoll, &lsquo;Wild Life of Orchard and Field&rsquo; (New York 1902); and the books of Audubon, Godman, Kennicott, Merriam, De Kay, Baird, Coues, Herrick and other naturalists.