658 MURIDA—MUS 
The Japanese have cultivated a breed of tame House Mice 
remarkable for their habit of running round and round in 
circles when in the open, whence they are called ‘dancing 
or waltzing mice.” In 1894 William Blasius showed specimens 
to Barrett-Hamilton, and informed him that two or three 
will join to make one composite circle, and thus have a 
tendency to damage each other’s tails; in apparent proof 
of which, Barrett-Hamilton noticed that the old mice had 
no tails, whereas a young one was well provided. These mice 
appeared to be tame white mice marked with black. Waltzing 
mice of various colours are known; in some the eyes are 
black, in others pink; the pink-eyed types breed true to that 
character. When exposed to light, such mice run round after 
their tails, spinning with great rapidity. Very often, if not 
invariably, the waltzing habit is correlated with a malformation 
of the internal ear, and ‘waltzers” are always of delicate 
constitution ; but the physiological cause of the habit is not 
well understood at present. From the experiments made by 
Von Guaita and Darbishire it would appear that ‘“ waltzers” 
behave as complete recessives when crossed with normal non- 
waltzing types.’ 
It is of interest to note that ‘ waltzing black rats” appeared 
in the course of Bonhote’s breeding experiments, with the 
progeny of a cross between &. 7. alexandrinus and E. +r. 
frugivorus (Proc. Zool. Soc., 1912, 6). These also proved to 
be very delicate. 
The nest of the House Mouse is composed of soft materials 
such as straw, hay, woollen and cotton rags, or paper; these 
Nature, xvii. 1877, 11 ; J. Sidebotham, zé7@., 29 ; G. J. Romanes, zézd., 29 ; Landois, 
Zool. Gart., 1871, 162, and Jahresb. Westfal, Verein., xi., 1882-3, 17 and 21; Struck, 
Arch. Ver. Mecklenburg, xxxv., 117; Lataste, Zooethigue, 1887, 287; Lockwood, 
Amer. Nat., 1871, v.. 761 ; Darwin, Descent of Man, 568, 865 ; A. H. Cocks, Bucks ; 
Douglas English, Some Smaller British Mammals, 84; Coburn, Journ. An. 
Behaviour, ii., 1912, 364, and iii., 1913,°388 ; and T. Coward, zm @z¢, to Barrett- 
Hamilton, 2nd July 1912. Numerous other references will be found in some of 
the papers cited—notably in those of Landois and Struck. 
1 See Von Guaita, Ber. Naturf. Ges, Fretburg., x., 1898, 317, and xi., 1900, 131 ; 
Darbishire, Biometrika, ii., 1902, 101, 165, 282, and iii., 1903, 1; Durham, Ref. 
Evol. Comm. Roy. Soc., iv., 1908, 41; Bateson, Mendel’s Principles of Heredity, 
1909, 33 and 111; Alexander and Kreidi, Monatschr. Ohrenheilk., Berlin, 35, 1901, 
78; Yerkes, The Dancing Mouse, New York, 1907 ; Quix, Amsterdam, Werk. Gen. 
Nat. Genees. Heelk., 1909, 83. 
