6 THE ENTOMOLOGIST. 
Bloxworth Heath. Two other specimens have been detected by 
the Rev. J. S. St. John, of Whatley Rectory, Frome, Somerset- 
shire, among a small collection of Lepidoptera he had obtained 
from a gentleman in his parish (vide Entom. xviii. 292). These 
last two specimens of L. argiades it appears were taken “ with 
several others’’ eleven years ago, that is, in 1874, close by a 
small quarry not two miles from the Rectory. Roughly speaking, 
Frome is distant from Wareham about forty miles as the crow flies. . 
Is Lycena argiades indigenous? or is its occurrence in 
England due to recent immigration? or to the conscious or 
unconscious agency of man? Whilst admitting the possibility 
of either of the latter contingencies, I incline to the opinion that 
L. argiades is a true native, and that it came into this country 
with such species as L. bellargus and L. corydon during the 
middle post-glacial epoch, at which period of time our islands had 
extensive land-connection with the Continent of Europe. It is 
probable, however, that LZ. bellargus and L. corydon were both 
somewhat in advance of L. argiades, and that all three were long 
preceded, perhaps in early post-glacial times, by ZL. icarus and 
L. e@gon. Later on, when our islands became again separated 
from the Continent of Kurope and the climate became colder, L. 
argiades would, supposing it to have spread over England, be 
driven, together with its congeners (except, perhaps, L. icarus and 
L. egon), southwards. 
During the geological period known as the late post-glacial 
epoch, various animals and plants which had come in from 
Central and South Europe in the middle post-glacial era, and had 
extended themselves northwards, would now by reason of the cold 
be compelled to retreat southwards. They would not be able to 
return to the Continent because of the sea-barriers. Under these 
circumstances many species would be destroyed, and others con- 
tinue a precarious existence on the most southern limits of our 
shores, where they would be brought into severe competition one 
with another. . argiades was probably one of those that just 
succeeded in holding their own until the return of a warmer 
period. When the climate became more genial this species would 
have to continue the struggle for existence, and it would find its 
stronger competitors among its near allies. Being the weaker 
species, it probably was never able to form such colonies in the 
South of England as L. bellargus and L. corydon have done, but, 
