A Study in Variation. 75 
be 51.44, this relation accounting for the late appearance of 
the specimens. The variation of 7.845 or 15.25 per cent, of 
the mean is low and indicates the low deviation within the 
confines of these factors. The range of form in the group 
shows a range of 39.5 per cent., the majority occurring above 
the mean. 
The variant depth and thickness show greater deviation 
than any of the others. Considering first the relation 
xioo. The mean relation is 42.48 and the arithmetic 
mean deviation is 9.34 or 21.98 per cent of the mean. The 
range is considerable, being 45.7 per cent. 
In the case of ±hi?*^xioo there is a mean value of 40.80 
and an arithmetic mean of 6.169 or *5-o8 per cent, of the 
mean. The range here is less than in any of the other variants, 
being only 39 per cent. 
The Scatter Diagrams. — The three scatter diagrams Figs. 
4 and 5 show that the correlated factors are the same in each 
of the species. 
The plotting of X 100 against ^~ h X 100 gives 
an even scatter over the four quadrants and thus shows the 
low correlation existing between the variants included in the 
1933 April 1 
