906 DB. A. G. BUTLBK ON BTTTTEKFLIES [NoV. 29, 



19. AcE^A NATALiCA Boisd. 



5 S , Salisbury, 2nd and 6th March, 1898. 



20. AcEiEA TiOLABUM and var. asema Hewits. 



d , ? ? , Salisbury, 5th March ; 9th, 24th, and 27th April, 

 1898. 



These, which represent typical A. asema (and should therefore, 

 according to Mr. Marshall, be the dry form of A. violarum), are 

 labelled " violarum-asema," but a female obtained on the 5th March, 

 which is almost as heavily marked as typical A. violarmn, is labelled 

 also in the same way though marked with the " wet " sign. To 

 my mind it belongs to the intermediate form, and I think conclu- 

 sively proves that A. asema is only a form of A. violarum. 



21. AcE-SA CALDAEENA Hewits. 



6 6, $ 2 , Salisbury, 19th February ; 2nd, 13th, 20th, 23rd, 

 and 26th March ; 20th and 30th Api"il ; 11th and 14th May ; 

 5th June, 1898. 



The seasonal differences appear to be slight in this species : the 

 male seems to differ only in the better marked border to the 

 secondaries in the wet-season, and the female in its smoky suffusion 

 sometimes accompanied by a white belt across the primaries ; but 

 at all seasons there seems to be a certain amount of variation even 

 in these characters, though the clouded females do not, apparently, 

 occur in the dry season. A male with very dry characteristics and 



labelled with Mr. Marshall's dry sign ^ was taken on the 26th 



March, and much wetter forms in April, when a wet male and dry 

 female were taken on the same day. It seems to me that these 

 facts are clearly in favour of my view that the seasonal forms of 

 butterflies existed originally as simple variations, and were 

 subsequently accommodated to seasons which afforded them most 

 protection. Thus the males of A. caldarena, which show no 

 striking seasonal differences, and which would be hardly more 

 conspicuous at one season than another, are inconstant in their 

 seasonal characters, whereas if the white-banded, smoky female 

 appeared in the dry season it would probably be very conspicuous. 

 It may be questioned as to what advantage a protected Butterfly, 

 such as an Acirea, could gain by being inconspicuous. Although 

 the species of this genus are said to be not only offensive, 

 but elastic and difficult to kill, it is certain that many are 

 permanently maimed by birds and reptiles which (presimiably) 

 seize them for the first time, or have not become satisfied of their 

 inedibility. 



L T C jE N I D iE, 



22. Al^na NTASsiE Hewits. 



Salisbury, 3rd and 16th April, 15th May, 1898. 

 One of the males, having white spotp in the cell, was wrongly 

 labelled ?. 



