424 Mr. G. A. K. Marshall on 



the lower, more shady slopes, the Avct on the upper 



slopes wliere there is less shade. 

 III. The following species only occurs (in Mashonaland) 

 in open country : — 



1. F. ccrync. Both forms are found in open swampy 



districts, without bush. Rare." 



E. Evidence of Adaptation in the conspicuous wider-sides oj 

 the Wet- Season Phases almost equal to the proof of it in 

 the cryptic Dry Phases. 



The evidence of adaptation in the cryptic under-sides of 

 the dry phase in the species under discussion is so clear 

 and so generally admitted that it is unnecessary to say 

 much about it. I will only point to the manner in Avhich 

 the various distinctive elements of this phase are co- 

 ordinated to a common end, that of concealment. Thus 

 in the dead-loaf-like forms such as archesia and antilope 

 we find the prolono;ed anal anijle of the hind-wiu", the 

 produced and bent apex of the fore-wing, the angulated 

 outline between these points, the stripe representing a 

 mid-rib, the colours and patterns varying in different 

 individuals but always resembling some type of dead leaf 

 with discoloured blotches or eaten into holes {archesia). 

 Most important of all there is the co-ordination of all 

 these diverse elements with appropriate habits and the 

 choice of an appropriate station. In archesia, which com- 

 monly frequents rocks, the intensely variable mottled 

 appearance produces a strongly cryptic effect at a little 

 distance, while a close inspection only brings out the details 

 which produce a graphic representation of a dead leaf In 

 sesamns the outline and umler-side differ from those of the 

 dead-lcaf-likc dry phases of the other species, and differ in 

 a direction which is specially cryptic, because of the peculiar 

 habits of this phase of the species (see pp. 420, 422). 



All this will be at once admitted by every naturalist 

 who studies the specimens, as it is proclaimed by all who 

 have had the advantage of observing the species in the 

 wild state. What is not admitted, but is I think almost 

 equally clear, is the fact that adaptation in the opposite 

 direction, viz. the direction of conspieuonsncss, is characteristic 

 of the undersides of the wet phase. If the under-side 

 merely reproduced the conspicuous pattern of the upper- 



