some British Bast African Butter Jiies. 531 



fined to the parts of the under surface which are visible at 

 rest: they probably sub-serve Miillerian mimicry during 

 repose. There can be no doubt that the resemblances in 

 question are based on affinity : comparison between the 

 cahiroides female form and honasia, F., the western 

 representative of alicia, makes this evident. But, at the 

 same time, it is equally clear that in the presence of the 

 British East African cahira, just those elements in the 

 pattern have been retained, developed and modified, which 

 would thereby promote resemblance during repose. 



Type captured, March 28, 1907, at Weithaga, N. Kikuyu, 

 British East Africa; in Hope Department, Oxford Uni- 

 versity Museum. 



The cahiroides form was taken in coitu with the male 

 A. alicia on March 20, 1907. 



Acrxa alicia, E. M. Sharpe, new female form tenelloides. 



Distinsjuishinor features are confined to the under surface 

 which is alone referred to below. The under surface of this 

 female form, which is apparently less abundant than cahi^ 

 Toides, superficially resembles that of the tenella, Rogenh. 

 { = ahl)otti, Holland), form of Acrxa vinidia, Hew., found 

 abundantly in the same locality (Weithaga). As in cahi- 

 roides, l\\e resemblance is confined to the parts of the under 

 surface that are visible during repose. The sharp demarca- 

 tion between the marginal markings and the paler ground 

 colour is obscured by an over-spreading ochreous shade, pro- 

 ducing an effect entirely different from that of the cahiroides 

 form and its model, but somewhat similar to i^cwc/Za, especially 

 the females. The cream-coloured band crossing the hind- 

 wing which is so conspicuous a feature in the cahiroides 

 form, is here obsolete or invisible, being of a pale yellow 

 tint like the rest of the disc. The marginal pattern 

 is much reduced, the inner part with its bay, which is 

 so characteristic a feature in cahiroides, being absent or 

 only to be made out by careful examination. Thus reduced, 

 the margin is only about half the width attained in the 

 other mimetic female form, being of about the same pro- 

 portion as in tenella, and like it with an internal contour 

 nearly parallel with the hind margin of the wings, and 

 with a bay which is slightly marked as compared with 

 that of cahira and its mimic. The triangular yellow inter- 

 nervular markings which invade the border from the hind 

 margin of the hind-wing resemble the similar orange 



TRANS. ENT. SOC. LOND, 1908. — PART III. (DEC.) 35 



