298 Professor E. B. Poiilton on Mimetic Forms of 



(omittioff from consideration the one that lias been acci- 

 dentally injured) possesses a pale brownish edging also 

 characteristic of the male. 



In the fore-wing the yellow male streaks and patches 

 are strongly developed on the disc below the cell. It is 

 deeply interesting to observe how sharply cut off they are 

 when, crossing the lower part of the fulvous baud, they 

 reach the black border. We are driven to infer that this 

 portion of the border almost precisely corresponds in the 

 two sexes and that the black border of this and other 

 female forms is inherited unchanged from an ancestor like 

 the male. In fact this character carries us further back 

 than the ancestral trimcni form (Plate XVIII, Fig. 1) in 

 which the male border has already been greatly modified. 

 It is to be observed furthermore that the abrupt termination 

 of the yellow streaks confers upon the black border a 

 sharpness of outline entirely wanting in the female form, 

 as is at once seen when the right and left sides are com- 

 pared. Opposite to the middle of the hind margin the black 

 border is invaded by an outward extension of the fulvous 

 band — due to that part of it which represents the sub- 

 apical bar of the Id'pfocoon % form (compare Figs. 2 and 4 

 on Plate XVIII). Here the ancestral male border has 

 been much reduced, and in the gynandromorphic specimen 

 the site of the invading fulvous concavity is in part covered 

 by grey scales quite distinct from the yellow ones on tliose 

 parts of the wing surface which are yellow iu the male. The 

 photographic method however only imperfectly renders 

 the difference. 



{r\) Mimetic relationship's and distrihution of plancmoides. 



This beautiful form, only recently recognized as a mimic 

 of Fknwmct jw/^^ct by Trimen and Neave (Proc. Ent. 

 Soc. Lond., Oct. 7, 1903,) is not known to occur as a 

 female form of any sub-species of dardamns except meropc 

 (= dardanus dardanus). The occurrence at Taveta of a 

 tine variety of Acr/va johnstoni (Plate XXI, Fig. 2 «) 

 strongly convergent toward s^j/cmcv^tccz'^ics renders it probable 

 that this latter exists in the neighbourhood, perhaps as 

 one of the female forms of the sub-species tilndlus. The 

 immense increase in our knowledge of plancmoides during 

 the last two or three years encourages the hope that we 

 shall at no distant date be fully acquainted with its range. 



