TABLES. 



123 



Table 68. 



Coefficients of variability of sixteen different skeletal dimensions of the females in the 

 guinea-pigs and hybrids. 



Table 69. 



Averages of the coefficients of variability of sixteen measurements in the hybrids 

 and guinea-pig.* 



*The probable errors were calculated from the formula: 



1 l~2 2 2 7 



Em = i -vl e -f- e -1- e -|- . . . e' 

 n \ 1 2 s ' n 



according to which the probable error of the average of a series of statis- 

 tical determinations is equal to the reciprocal of the number of determi- 

 nations into the square root of the sum of the squared errors of the 

 individual determinations. 



Table 70. 

 Occurrence of an interparietal bone. 



