338 Mr. G. A. K. Marshall on the Genus Byblia. 



especially along the coast-belt, it is the prevailing 

 form, typical ilithyia only occurring very rarely, 

 whereas on the plateaux of the interior the position is 

 exactly reversed. This distinct localization of the 

 two forms, combined with tlie fact that 1 have never 

 been able to find any intergrades linking them together, 

 led me at one time to believe they were specifically 

 distinct ; but the matter has now been decided by the 

 fact that Mr. Hutchinson in April last bred a specimen 

 of the wet-season form of the var. achelo'ia {=^ vulgaris) 

 from an egg laid by typical ilithyia. In April 1893 

 I took a very curious sport of this variety on the 

 Biggarsberg (about 5000 feet), in Natal, in which the 

 underside of the hind wings was of a deeper ferru- 

 ginous than usual and had completely lost all trace 

 of the three white bands. 



{b). Var. goetziusj Herbst. 



This is essentially the West Coast and Central 

 African variety and differs chiefly from achelo'ia in 

 having the hind marginal black bar of the fore wing 

 continued right up to the costa, so as to give it the 

 appearance of a broad marginal border enclosing a 

 row of small spots of ground-colour similar to that in 

 the hind wing. This, however, is a variable character, 

 and every intergrade can be found linking it to 

 achelo'ia^ though the extremes present a very different 

 appearance. Herbst's figure of his male goetzius 

 (Nat. Insek. Schm. ix. t. cclviii. figs. 1 and 2) clearly 

 represents a specimen of typical ilithyia^ the female, 

 however (figs. 3 and 4), representing the type of his 

 variety. 



(c). Var. castaneay Btitler. 



This is the north-eastern variety, being recorded at 

 present only from Abyssinia, Somaliland, and Aden. 

 It was founded on dry-season specimens, and that is 

 the only form that I have seen. On the upperside it 

 resembles var. achelo'ia, but has much narrower discal \ 

 bhack bands, and consequently much larger submar- 

 ginal spots in secondaries ; the central white band on 

 the underside of hind wings is distinctly angulated, 

 thus constituting an interesting link to the Madagascar 

 subspecies B. ilithyia-aiivatara, Boisd. 



In the upper districts of Natal the food-plant of B, ilithyia 



