COEF) [Ixii, Ixiii, Ixvi 
re the ‘wet season’ and ‘dry season’ phases of these butter- 
flies, that, as has also happened in many other cases, they 
have been described under different names, and are even now 
pretty generally ranked as separate species. It may therefore 
not be amiss to recall the fact that in the case of three out 
of the four it has been absolutely proved by Mr. G. A. K. 
Marshall, who has bred them through, that the two seasonal 
forms are conspecific (see Trans. Ent. Soc. Lond., 1902, 
pp. 200, 209-212). 
“There remain two further points that seem worthy of 
note. One is that, as will be easily evident on inspection, 
our Natal forms, though distinctly of the ‘dry season’ type, 
are appreciably less extreme in that direction than are our 
Rhodesian representatives of the same species. This corre- 
sponds with the much more markedly dry meteorological 
conditions that we found prevailing in the latter locality. 
The other point is that, even in cases where the wet-season 
males of two species, such as 7. omphale and 7. achine, are 
quite unlike one another, the resemblance between the dry- 
season males of the same two species may be so close that 
in the field they can only be distinguished with difficulty.” 
Colonel J. W. Yersury said that in his opinion the term 
*‘seasonal” when applied to developments of this kind was 
misleading. The variation of the forms seemed to depend 
not upon fixed seasonal conditions, wet or dry weather, but 
upon the amount of moisture and light to which the species 
were subjected, probably in the pupal stage. 
Professor E. B. Pounron understood that the term “‘ season ” 
as used in this connection, referred to the climatic conditions 
which prevailed at the time. He considered that ‘“ wet 
form” and “dry form” were more accurate expressions than 
‘wet season form” and “ dry season form.” 
Wednesday, December 6th, 1905. 
Dr. F. A. Dixy exhibited examples of five species of South 
African Pierine, in further illustration of geographical and 
seasonal variation. The exhibit, which was supplementary to 
