2 The Dancing Mouse 



mouse into a really admirable animal. The Japanese 

 dancing mice, which perfectly justify their appellation, also 

 occur in all the described colors. But what distinguishes 

 them most is their innate habit of running around, describing 

 greater or smaller circles or more frequently whirling around 

 on the same spot with incredible rapidity. Sometimes two 

 or, more rarely, three mice join in such a dance, which usually 

 begins at dusk and is at intervals resumed during the night, 

 but it is usually executed by a single individual." 



As a rule the dancing mouse is considerably smaller than 

 the common mouse, and observers agree that there are also 

 certain characteristic peculiarities in the shape of the head. 

 One of the earliest accounts of the animal which I have found, 

 that of Landois (22 p. 62), states, however, that the peculiari- 

 ties of external form are not remarkable. Landois further 

 remarks, with reason, that the name dancing mouse is ill 

 chosen, since the human dance movement is rather a rhyth- 

 mic hopping motion than regular movement in a circle. As 

 he suggests, they might more appropriately be called "circus 

 course mice" (22 p. 63). 



Since 1903 I have had under observation constantly from 

 two to one hundred dancing mice. The original pair was 

 presented to the Harvard Psychological Laboratory by 

 Doctor A. G. Cleghorn of Cambridge. I have obtained speci- 

 mens, all strikingly alike in markings, size, and general 

 behavior, from animal dealers in Washington, Philadelphia, 

 and Boston. Almost all of the dancers which I have had, 

 and they now number about four hundred, were wKite with 

 patches, streaks, or spots of black. The black markings 

 occurred most frequently on the neck, ears, face, thighs, hind 

 legs, about the root of the tail, and occasionally on the tail 

 itself. In only one instance were the ears white, and that in 

 the case of one of the offspring of a male which was distin- 



