210 Mr. S. A, Neave : some bionomic 



It is therefore fairly safe to say, even considering the 

 comparatively small number of specimens measured, that 

 there has been a marked increase in the size of this spot 

 as we advance northward along the East Coast, and thence 

 turn westward to the apparent limit of the area of dis- 

 tribution of the species. In addition to this increase in 

 area of the spot, which is common to both species, it is 

 fairly evident from the above table that there is an increase 

 of a peculiar kind, the spot becoming distinctly more 

 circular in shape as we proceed westward. As will be 

 seen from the table, the ratio of breadth to length is 

 appreciably greater in both species west of the Lake than 

 east of it. In A. alhimaculata this progressive increase 

 occurs as we come up from the south, as well as from 

 east to west. 



Other points of superficial resemblance which both 

 species share, are greater expanse of wings and much 

 better development of submarginal spotting on the hind 

 wing. As might be expected, the resemblance in the ^ $ 

 is markedly closer than in the $ $. The $ specimen of 

 aJbimaculata from Toro, figured, shows this resemblance in 

 an astonishing manner, and has the additional character- 

 istic of the pale buff area at the base of the hind wing 

 being somewhat diffused. This resemblance becomes all 

 the more significant when we remember that A. fsyttaha 

 does not occur in South Africa, while it is a very dominant 

 species in Uganda, and also occurs, but not so commonly, 

 in British East Africa. I have not had an opportunity of 

 comparing numbers of specimens of A. psyttalca from the 

 east and west shores of the Lake, but it is undoubtedly 

 very common, and occurs in the Wiggins collection from 

 every locality except the more open plains. 



This clear influence that the presence of one species has 

 had upon two other closely allied ones (all being highly 

 distasteful), seems to be one of the most striking examples 

 of Mullerian mimicry that it is possible to imagine. 



The specimens of A. psiittaka are themselves remarkably 

 interesting, the species being apparently in rather an 

 unstable condition. The majority of the specimens, 

 especially from the more eastern localities, are of the form 

 damoclidcs, Stand,, but a number from the north-west of 

 the Lake are typical A. psyttalea, Plotz, from the tropical 

 Atlantic Coast. These specimens, which are accompanied 

 by many intermediates, are distinguisheil from A. psyttalca 



