30 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
1888, the last, the best studied, the most notorious year 
of their abundance. ‘The imago is out perhaps at the end 
of May on the continent and must have been blown across 
during June and July to be present here at the time when 
the few captures here were made. Then there ought to 
have been during that time winds continuous or at any 
rate frequent from the south east or east. But as a matter 
of fact the prevalent winds during those two special months 
were west, north west, and south west and only on about 
ten isolated days did the wind blow from the requisite 
quarter. In fact this particular summer which brought 
the moths had less east and south east winds than almost 
any of the preceding eighteen years which brought no 
moths. There are other difficulties besides this to sur- 
mount, thus the wind cannot be supposed to be dis- 
criminative in its effect. Allow a cloud of moths wind 
driven from the Dutch coast, and carried bodily across the 
German Ocean, their disposition on arrival must be purely 
mechanical, we should have individual moths rather 
battered and worn, distributed indiscriminately all over 
England more in the eastern coast and thining out as one 
proceeded westward. What are the facts? nothing like 
this. We have a great many moths fresh as though just 
emerged from the pupe segregated in particular small 
localities, more actually occurring in a spot of a few acres 
almost as far west as one could get, than in all the country 
between Thames and Tweed. Such considerations seem 
to me to effectually dispose of the wind blown theory. If 
we had only the case of Devlephila galw in Kent and 
Essex I should admit the hypothesis to be not utterly 
untenable, but it is its presence here in Cheshire and in 
Ireland which it is impossible to reconcile with a distri- 
bution caused solely by the agency of wind. 
But another and still more startling explanation has 
