noks on Bntterfiics from the Victoria Nyanza. 211 



damoclidcs by a reduced pale area at the base of, and the 

 absence of submarginal spots on the hind wing, giving 

 them a marked general resemblance to western forms 

 such as A. damoc/es, Beauv. (non Fabr.), and hccate, Butler. 

 A. hccate does itself occur sparingly on the shores of the 

 Lake ; as also another species allied to it, viz., the recently- 

 described A. dim, mihi (2).* In this species all the white 

 markings and (especially the pale area at the base of the 

 hind wings) are even more reduced than in hccate. 



The above is a striking case of a species acting as a 

 model, at one and the same time as certain individuals of 

 it are being attracted into another group. This compli- 

 cated condition of mimetic association in which a species 

 is both model and mimic at the same time is well known 

 to be paralleled in the Neotropical region, where we find 

 similar but still more complicated instances among the 

 Danainx, Heliconinie and Ithomiina',. 



The specimens of Amauris niavitts, Linn., are also deeply 

 interesting. Whilst the specimens taken west and north- 

 west of the Lake (with one exception from Entebbe which 

 is intermediate in character) are all A. niavius niavius, 

 the typical western forms, those from the north-eastern 

 shores numbering about thirty specimens are nearly fifty 

 per cent, of them intermediate to A. niavius dominicanus, 

 which occurs at Mombasa. 



The two chief points of distinction in the latter form 

 are the greater extent of all the white areas and spots on 

 both wings. The spot within the cell and subapical bar 

 of the fore wing, together with the white basal area of the 

 hind wing, are especially larger. In A. niavius niavius 

 the discocellular spot is evanescent, and the Avhite basal 

 area of the hind wing seldom even reaches the extremity 

 of the cell. 



The specimens above mentioned occurring from the 

 east of the Lake are remarkably intermediate in respect 

 of these characters. The discocellular spot is well marked 

 but not so large as in dominicanus. The subapical white 

 bar is broader than in niavius, but not so broad as in 

 dominicanus. The basal white area of the hind wing 

 extends well beyond the extremity of the cell, but not 

 nearly so far as it does in dominicamis. 



The two instances above of two geographical forms of a 

 species meeting and appearing in an intermediate form on 

 * Loc. cit. p. 324. 



