40 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
only a little over two inches. The moths then as regards 
their ovipositing powers seem to be quite indifferent to 
much or little wet. Then one might naturally surmise 
that the ova or very young larve might be highly suscep- 
tible to continued dampness, but we find no evidence of 
this, in fact there are only two Augusts, (the month of 
ova and young larvee) out of all the series, and that the 
least valuable from an evidential pomt of view which were 
particulary dry, I mean 1833, 1834. But now if a later 
period in the larval life is considered, say the last half of 
it, we may perhaps discover some sort of uniformity. 
The Octobers of what I believe to be the critical part of 
the term are dry, uniformily, consistently dry. Only one 
comes to above half the mean of the rainfall of 50 years. 
Now I think that it is at least a not untenable hypo- 
thesis, to conclude that the mature larva of this moth is 
particularly susceptible to continued rain and dampness, 
that such a state of the atmosphere occasions great mor- 
tality among these larve, that as the months of September 
and October are nearly always wet with us, there is 
consequently nearly always a heavy mortality, but that 
on those very exceptional years when we have a particu- 
lary dry autumn, a much greater number of larvee survive, 
and that such increased larval survivals result, nothing 
occurring of a specially detrimental effect meanwhile (and 
this of course is an important proviso), In an increased 
number of imagines, and it is the progeny of these imag- 
agines whose numbers arrests our attention and make 
what we a call galv year. 
Now it is not necessary that this second brood of larvee 
survive; to attest their abundance they have but to exist 
up to a certain point; therefore if any object that there 
were wet Octobers in 1859 and 1870 years when the larvee 
were abundant, my answer is that I freely admit the wet 
