Characteristics, Origin, and History 3 



guished from most of his fellows by the possession of one 

 white ear. I have had a few individuals whose markings 

 were white and gray instead of white and black. 



The method by which I was able to keep an accurate 

 record of each of my dancers for purposes of identification and 

 reference is illustrated in Figure i. As this method has 

 proved very convenient and satisfactory, I may briefly de- 

 scribe it. With a rubber stamp * a rough outline of a mouse, 

 like that of Figure i A, was made in my record book. 

 On this outline I then indicated the black markings of the 

 individual to be described. Beside this drawing of the ani- 

 mal I recorded its number, sex, 2 date of birth, parentage, 

 and history. B, C, and D of Figure i represent typical 

 color patterns. D indicates the markings of an individual 

 whose ears were almost entirely white. The pattern varies 

 so much from individual to individual that I have had no 

 trouble whatever in identifying my mice by means of such 

 records as these. 



All of my dancers had black eyes and were smaller as 

 well as weaker than the albino mouse and the gray house 

 mouse. The weakness indicated by their inability to hold 

 up their own weight or to cling to an object curiously enough 

 does not manifest itself in their dancing; in this they are 

 indefatigable. Frequently they run in circles or whirl about 

 with astonishing rapidity for several minutes at a time. 

 Zoth (31 p. 173), who measured the strength of the dancer 



1 For the use of the plate from which this stamp was made, I am in- 

 debted to Professor W. E. Castle, who in turn makes acknowledgment to 

 Doctor G. M. Allen for the original drawing. 



2 I have found it convenient to use the even numbers for the males and 

 the odd numbers for the females. Throughout this book this usage is 

 followed. Wherever the sex of an individual is not specially given, the 

 reader therefore may infer that it is a male if the number is even ; a female 

 if the number is odd. 



