414 
Mr. Cecil W. Barker^s 
the same butterfly. It is in these doubtful cases that 
I hope to show how the tendencies of dry season forms 
to modify, according to certain fixed rules, may assist in 
the determination of these as either true species or 
varieties. 
The reason for these seasonal modifications it is more 
difficult to understand. That in some cases the duUer tints 
of the underside of the wings, adopted by the dry season 
forms, may serve for protection, is a very generally 
accepted opinion, and is perhaps borne out by the fact that 
the Danainge and Acrseinse, protected species, either do not 
modify according to the season, or, where there is some such 
modification, it is not in favour of duUer tints. Thus in 
Acrsea petrseaj ? , the summer form is dark brown, whilst 
the dry season form is invariably red like the $ . 
Therefore, whether this change or modification of 
facies of dry season forms is due to protective mimicry, 
or whether it is the mere sympathy of organisms with 
their surroundings, it is beyond my knowledge or scope 
to determine. 
Subfamily Satyrin^. — Mycalesis perspicua in the 
dry season form exhibits very marked contraction of 
some of the ocelli of the underside and the obliteration 
of others. 
Mycalesis safltza follows the same rule, and also shows 
local modification of a similar kind, probably due to the 
drier and less luxuriant character of the country in 
which these modifications occur — ^er exemplum^ the 
variety M. evenus (Hopfi*.) is alone found in the Knysna, 
which is the southern and western limit of this butterfly 
in the Cape Colony (Trimen, ^^South African Butterflies^^). 
Subfamily Ntmphalin^. — Atella phalantha is on the 
wing both in summer and winter, and shows seasonal 
modifications. 
Thus all the fuscous markings and spots of the 
upperside are contracted in the dry season examples, 
and they also exhibit a disposition to suflfusion of the 
markings and spots of the underside and a duller 
ground-colour. Junonia clelea in its dry season coat 
adopts a duller and darker underside. 
Precis cloantha exhibits attenuation of the upperside 
fuscous markings and a darker underside. P. elgiva 
exhibits the same tendency. Crenis hoisduvali modifies, 
but in a lesser degree. C. natalensis ditto. Eypanis ilithyia, 
