306 Professor E. B. Poulton on Mimetic Forms of 



We see therefore that Aurivillius keeps ^. /^/coa distinct, 

 wliile he suggests that A.fallax (Idliinandjara) may be a 

 form of j'ohnsloni. I believe that he is right in this last 

 opinion, although positive proof can only be gained by 

 breeding ; but the facts set forth below render it certain 

 tliat fallax is the eastern form of li/eoa. If Aurivillius is 

 right in his association of fallax it will inevitably follow 

 that the whole series of varied forms must fall under 

 Godart's species, — lycoa. 



AcTiva lycoa of the tropical west coast is distinguished 

 from A. jolinstoni by the following characteristics : — 



(1) The large size of the four spots on the fore-wing 

 and the tendency of the subapical pair to fuse and form 

 a subapical bar : the tendency of the more interior pair 

 similarly to form a patch extending from below the end of 

 the cell towards but not quite reaching the posterior angle 

 of the wing. The spots are, however, sometimes separate, 

 although much larger and more nearly approximated than 

 in johnstoni. 



(2) The pronounced sexual dimorphism of which no trace 

 can be found in Johnstoni. The males of lycoa have a 

 much browner ground colour than the females, especially in 

 the hind-wing, while the spots of the fore-wing are pale 

 buff instead of white and are sometimes evanescent. 

 Furthermore the white discal patch of the hind-wing is 

 unrepresented in those males I have had the opportunity 

 of examining, while the development of the internervular 

 radii is correspondingly increased. 



(3) The apex of the fore- wing of lycoa is more broadly 

 rounded and the costal margin more curved than in 

 johnstoni. The outline of the wing between the apex 

 and the posterior angle is straight or even convex in the 

 females, straight or very slightly concave in the males. 

 In A. johnstoni it is probably always concave, although 

 sometimes very slightly so. 



(4) The basal black sjDots on hind-Aving under-side are 

 smaller in lycoa and less concentrated towards the extreme 

 base of the wing. The spot in the base of the cell with 

 the two spots on the costal side of it forms in lycoa a 

 characteristic approximately equilateral ti'iangle. Owing 

 to the greater concentration of spots the corresponding 

 triangle in jolmstoni is nearly always isosceles with its base 

 towards the root of the wing. It is moreover less con- 

 spicuous as a feature in the wing of this latter form. 



