582 Wm. E. Kellicott 



percentages varying from 11.4 in length of head to 56.7 in total 

 weight. This same distinctness between the sexes was found in 

 the calculation of all constants and consequently they were treated 

 separately throughout. 



Second, there is a corresponding distinctness between the males 

 and females with respect to the amount of variability. The coeffi- 

 cient of variability may now be accepted as a thoroughly reliable 

 measure of comparative variability. As expressed by this coeffi- 

 cient the females show a uniformly higher variability. On the 

 whole the females are about 2J per cent more variable than the males, 

 the actual percentages varying from 6.6 in weight of liver to 38.4 

 in length of body. 



Finally, inspection of the coefficients of variability shows that 

 the characters are separable into two quite distinct groups. The 

 external dimensions show not only a comparatively low degree of 

 variability but a remarkable uniformity, the limits of C being, 

 with a single exception, 6.0 per cent and 8.8 per cent. The other 

 characters, which we may call "internal" are several times more 

 variable and show much less uniformity, the limits of C being 9.8 

 per cent and 53.2 per cent. Excluding the total weight, total 

 length and length of leg as composite characters, we find that the 

 average coefficients of variability of the external and internal char- 

 acters are as follows : 



External characters. 

 Internal characters . 



That is, the internal characters are roughly four times as variable 

 as the external characters. 



It is an important consideration that, in spite of the very consid- 

 erable disparity in absolute size of the two sexes, the ratios between 

 the average values of pairs of characters are remarkably similar 

 in male and female series. Table III gives a few of these ratios 

 between characters measured in similar units. The ratios are 

 extremely close throughout, particularly those between charac- 

 ters which are obviously quite closely related in function, the body 

 and leg dimensions, for example, where the ratios are the same 



