MAMMALS THAT GNAW. 105 



elongated, both the eyes and ears large, the extremity of the muzzle naked, 

 the fur soft, occasionally mixed with spines, a flat nail on the first toe of the 

 fore-foot, the long and nearly naked tail covered with overlapping rings of 

 scales, and cheek pouches absent. The species found in Britain are the 

 common rat (M. decumanus), which appears to have been originally a native 

 of Western China, but has now been introduced into all parts of the habitable 

 globe ; the smaller and sharper-nosed black rat (M. rattus), which is likewise 

 an Eastern form ; the conxmon house -mouse (M. tnusculus), also hailing from 

 the East ; the wood-mouse (M. sylvaticus), together with a larger variety 

 known as M. flavicollis ; and the tiny harvest-mouse (M. minutus). The 

 latter, it is well known, builds small globular nests between several corn- 

 stalks, and is itself able to ascend a single one of such stalks, aided in 

 climbing by its partially prehensile tail. It will be unnecessary here to refer 

 to the habits of mice in general, but some reference may be made to the so- 

 called "singing" and "waltzing mice." Singing mice are ordinary house- 

 mice, which, owing to some disease of the vocal organs, are enabled to pro- 

 duce musical notes. Waltzing mice are a Japanese product, of which the 

 following account is given by Mr. E. R. Waite : "At first," he writes, " a 

 visitor probably regards the mice as mere colour varieties of the common 

 white race. A moment's observation reveals the peculiarities of the breed, 

 and attention is riveted by their strange performances. Early in life they 

 exhibit the tendency which has earned for them the name above employed. 

 When a nursling leaves the nest its gait consists of an evident attempt to 

 proceed in a straight line ; this is frustrated by a tremulous movement of the 

 head, which is nervously shaken from side to side. Shortly, a tendency is 

 exhibited to turn ; this develops into a rotatory motion, performed with 

 extraordinary rapidity, which constitutes the peculiarity of the waltzing 

 mouse. The ordinary routine of daily life is constantly interrupted by this 

 mad disposition to whirl, frequently indulged in for several minutes, and, 

 with an occasional stoppage of a few seconds, continued for hours. The floor 

 of one cage being somewhat rough, the mice actually reduced their feet to 

 stumps before it was noticed. Like ordinary mice, they sleep during the 

 day, 'but apparently waltz the whole night long. If, however, they are dis- 

 turbed during daylight, they leave their bed and work off some superfluous 

 energy. The rotation is so rapid that all individuality of head and tail is lost 

 to the eye, only a confused ball of black and white being recognised. Very 

 often they spin in couples, revolving head to tail at such a speed that an un- 

 broken ring only is perceived. . . . An individual generally spins in one 

 direction only, and the majority turn to the left." Although probably due 

 in the first instance to brain-disease, the peculiarity, like the " tumbling " of 

 tumbler-pigeons, is now hereditary in the breed. 



The longitudinally-striped Barbary mouse (M. larbarus\ together with 

 certain other more or less variegated African species, are frequently separated 

 from Mus as a distinct genus, under the name of Arvicanthis. Nearly allied 

 are the numerous species of bandicoot-rats (Nesocia\ ranging in Southern Asia 

 from Palestine to Formosa, and from Ceylon to Kashmir, but also extending 

 into Turkestan and the Lob-nor district of Central Asia. They differ from 

 the typical genus by the wider incisors and molars ; the tubercles on the 

 latter being partially connected by transverse ridges so as to produce a semi- 

 laminated type of structure. The two species of groove-toothed mice 

 (Golunda), one of which is Indian and the other African, are easily dis- 

 tinguished by having a groove down each of the front incisors. In addition 



