The genus Muscardinus includes only the Common Dormouse, M. arellanarius. This small creature, 3 inches long with a tail of 2½ inches, is, of course, a well-known inhabitant of this country. It is also found all over Europe. It is not particularly abundant in this country, and a good specimen is said to be worth half a guinea. As the specific name denotes, it lives largely on hazel nuts; but it will also suck eggs and devour insects. The animal makes a "nest" in the form of a hollow ball. Its hibernation is well known, and has also given rise to the German name ("Schläfer") of the group. It was well known to Aristotle, who gave or adopted the name Ἐλειὸς for the animal. Its winter sleep—suggestive of death—and its revivification in the spring gave the Bishop of Salamis, Epiphanius, an argument for the resurrection of man. The fur was reckoned in Pliny's time a remedy for paralysis and also for disease of the ears.
The genus Myoxus includes also but a single species, M. glis, the so-called "Fat Dormouse" of the Continent. It has no
glandular swelling at the base of the oesophagus, such as occurs in the last genus and in Graphiurus. Of Graphiurus there are thirteen species, all African in range. The genus does not differ widely from the last. There is, however, a glandular region of the oesophagus. Eliomys is the last genus of typical Dormice. It is Palaearctic in range.
Platacanthomys, of a Dormouse-like form, has like other Dormice a long tail, on which the long coarse hairs are arranged in two rows on opposite sides towards the tip; it is represented by a single species, P. lasiurus, from the Malabar coast. It is arboreal in habit. The fur is mingled with flattened spines. The molars are reduced to three on each side of each jaw. This form has been bandied about between the "Mice" and the "Dormice"; but Mr. Thomas's discovery of the absence of the caecum argues strongly in favour of its correct location among the Gliridae. Typhlomys is an allied genus, also from the Oriental region. This and the last are placed in a special sub-family of the Gliridae, Platacanthomyinae, by Mr. Thomas.
Fam. 2. Muridae.—This family, that of the Rats and Mice in a wide sense, is the most extensive family of Rodents. In it Mr. Thomas includes no less than seventy-six genera. The molars are generally three. The tail is fairly long, or very long, and the soles of the feet are naked.
Sub-Fam. 1. Murinae.—The true Rats and Mice may be considered to form a sub-family, Murinae. The genus Mus, including the Rats and Mice in the limited sense of the word, contains about 130 species. They are exclusively Old World in range, being only absent from the Island of Madagascar. In the New World there are no species of the restricted genus Mus. The eyes and the ears are large; the pollex is rudimentary, and bears a nail instead of a claw. The tail is largely scaly. All the members of the genus are small animals, some quite minute. In this country there are five species[[329]] of the genus, viz. the Harvest Mouse, M. minutus, which has a body only 2½ inches long with an equally long tail. It is the smallest of British quadrupeds with the exception of the Lesser Shrew. The Wood Mouse, M. sylvaticus, is about twice the size; it differs also from the last species in that it
frequents barns, and is thus sometimes mistaken for the Common Mouse, from which, however, it is to be distinguished by its coloration and longer ears. The latter, M. musculus, is too familiar to need much description. A curious variety of it has occurred. This has a thickened and a folded skin like that of a Rhinoceros, and the hair has disappeared. The Black Rat, M. rattus, is like a large Mouse, and is smaller and blacker in colour than the "Hanoverian Rat." It is sometimes called the "Old English Rat," but seems nevertheless to be not a truly indigenous Rodent. It has been so defeated by competition with the Hanoverian Rat that it is now not a common species in this country.
The Hanoverian or Brown Rat, M. decumanus, is a larger and a browner animal than the last. It is very widely distributed through the globe, no doubt largely on account of the fact that it is readily transported by man. The same is the case with the Common Mouse, whose real origin must be a matter of doubt. The original home of the Brown Eat is thought by Dr. Blanford to be Mongolia. There is so far a justification for the name "Hanoverian Rat" that the animal seems to have reached this country about the year 1728. But there is no reason for calling it, as is sometimes done, the Norway Rat.
Some members of this genus, whose fur is interspersed with spines, or which are quite spiny, have been separated as a genus, Leggada, which, however, is not generally allowed.
Closely allied again is Chiruromys, which has a strongly prehensile tail, a feature which is not common among the Myomorpha, though Dendromys, a tree-frequenting form, and Mus minutus, already spoken of, show the same character. Many Mice seem to have prehensile tails, which they can curl round branches; but it is not so fully developed as in the species just named.