60 A Study in Variation. 
In Fig. 3 are the four graphs shewing the variation in the 
two species. 
After the separation of the two species the graph of the 
variation of each was superposed on the original graph and 
appears in each polygon. Fig. 3 A shews only the one graph, 
since the variation is almost identical in the two species with 
respect to these two factors. The two mean values for these 
species are : Pugnax pugnus Martin, 78.88. 
Pugnax cf. sulcatus J. de C. Sow, 79.83 indicating a very 
slight tendency on the part of P . cf. sulcatus J. de C. Sow to 
a quadrate section. Little useful purpose would be served 
in separating these two in respect of these variants. 
Plotting the two variants as ordinates of a scatter 
diagram Fig. 6 shews that there are limiting curves within 
The Naturalist 
