522 Dr. A. G. Batler on Seasonal Dimorphisra, 
practically from tlie same cause, and in some cases it 
will be very hard to draw the line between them : a 
uniformly moist locality may produce only a wet-season 
form, and a dry locality the converse ; yet one could 
hardly speak of Acrsea pseudegina as a seasonal form of 
A, natalica, but merely as a western development of 
that species (an intermediate form completely linking 
the two extremes occurs in Angola) . 
Whether the colour variations of Acrsea johnstoni and 
other members of the A. esehria group are seasonal 
seems doubtful ; indeed, from the evidence before me, I 
should say — certainly not ; for we have extreme forms^ 
collected within three days, that is to say, with only one 
day's interval between, and, moreover, both forms are 
in admirable condition. The species of the A. esehria 
group are therefore probably simply inconstant, no 
satisfactory reason for such inconstancy being at present 
known, or even guessed at. 
The above observations will, I hope, help to impress 
upon collectors the importance of noting not only dates 
of capture of every specimen which they obtain, but also 
the altitude and nature of climate, so that Lepidopterists 
may have some definite data to work from in deciding 
these interesting questions touching the climatic re- 
lationships or seasonal dimorphism of the insects which 
come into their hands. 
i 
