204 THE AMERICAN NATURALIST [Vol. LII 



ponderance in the number of vertebrae is only 9 per cent. 

 The differences in the length of this appendage are there- 

 fore due partly to the number of vertebrae, but chiefly to 

 the length of the individual vertebrae. 



Resume of Racial Differences.— In relation to the vari- 



ous pigmental differences, those both of intensity and e: 

 tensity, the four races under consideration were found 

 present the following graduated series: 



Eureka > Berkeley > La Jolla > Victorville. 

 As regards the length to the tail, the series became : 

 _ , T -r „ ^ f Berkelev, 

 Eureka > La Jolla > j victorvHle 



