J. W. H. Harrison 



63 



straggle beyond the Palaearctic area. Both, therefore, as we may 

 glean, occur in Europe and Asia but, despite this, must not be regarded 

 as having colonised precisely the same territory within these continents. 

 T. bistortata is much the hardier and more adaptive insect, and therefore 

 manages to maintain itself in much more northerly stations than its 

 congener. 



Fi^. 1. Genitalia of Tephrosia crepuscular ia. 

 A=Valvae, etc. ; B = iEdceagU8 ; C = Signum of female bursa copulatrix 



Again, when they do occupy the same ground, they vary along 

 different lines, and each produces its own local races. For instance, in 

 North Durham T. bistortata is of the heavily barred Scottish form whilst 

 T. crepuscularia is of the pale southern English type ; yet in South 

 Durham and in the adjoining Cleveland District of Yorkshire the 

 former remains much the same whilst all the examples of the latterl 

 have seen appertained to the melanic variety delamerensis B. White. '' ■ 



