Coren [Ixxxvi, lxxxvil 
season he pointed out that in Rhodesia the species of Acrxa 
fall roughly into two groups in this respect, namely: (1) the 
larger or more high-flying species, such as acrita, anemosa, 
atolmis, etc., which presented a more brilliant appearance in 
winter ; this being probably due to their greater unpalatability, 
which had been to some extent shown by experiments, and 
which would render a bright aposematic coloration of consider- 
able utility at this season of greater stress; and (2) the 
smaller, low-flying, and less unpalatable species, such as 
axina, asema, ete., which could not afford to make themselves 
too conspicuous at such a time and whose colouring therefore 
tended more to harmonise with the dull reds and yellows of 
the withered grasses among which they flew. 
The question however of the significance of the black mark- 
ings in Acrxa was complicated by the fact that in several 
widely-distributed species there was a progressive local in- 
crease in the black from south to north, irrespective of season. 
Professor E. B. Poutton, F.R.S., congratulated Mr. Neave 
upon his interesting exhibition. He made a few remarks 
upon the melanic forms of the wet season, but expressed him- 
self unable at present to understand the full significance of 
the changes. In conclusion, Professor Pouuton asked Dr. F. 
A. Dixey whether it was likely that the females of Teracolus 
regina exhibited in one season a synaposematic approach to 
the females of other and very distinct species of the same 
genus ; in the other season a similar approach to Pierine of a 
remote genus. 
Dr. F. A. Drxry said that he was not at present prepared 
to give a complete answer to the question put to him by 
Professor Poulton. The seasonal changes of Z'eracolus regina, 
in relation to the sexual dimorphism of that species, were very 
remarkable and required further investigation. He had, how- 
ever, no doubt that both in this species and in 7’. phlegyas the 
dry-season form of both sexes had a cryptic character, at any 
rate in the resting position of the insect. He was quite con- 
vinced of this in the case of the last-named butterfly and of 
its congener, 7’. speciosus, from having watched both species 
under natural conditions. 
