iL) 
probable theory, together with my characterisation of the differences, 
then the same causes have evidently in time produced “ representa- 
tive” species as have operated to produce parallel species. But with 
the first class we can better measure the result, we can more surely 
prove a change to have taken place at all, if we can say 7: sz and 
T. occidentalis were one species before the glacial epoch. So that 
here, too, we should have a proof that species have originated through 
variation produced by the total surroundings. The identical species 
have resisted change ; they have “survived” under fresh conditions. 
Flehiothis phlogophagus may be cited as a typical “ representative ” 
species (of AZ. dipsaceus), because it produces also a ‘ representative ” 
variety. This tendency to produce a variety with yellow secondaries 
(both the black markings and the yellow ground are very vivid in 
/utettinctus) 1s an indirect proof of the relationship in my opinion, 
although yellow is a common colour in the hind wings in this group. 
This paper is, I think, a fair summary of the results yet obtained, 
and I hope exhibits the “present state of our ignorance,” as Mr. Tutt 
so happily expresses it, in an impartial manner. 
