THE GEOGRAPHICAL DISTRIBUTION OF THE 

 MOTHS OF THE SUBFAMILY BISTONINAE. 



J. W. HESLOP HARRISON. D.Sc. 



XV.— THE GENERA PHTHONOSEMA (WARREN), 

 EUBYJA (WARREN), APHILOPOTA (WARREN). 



Phthonosema tendinosaria (Brem.). Distribution : — The 

 Ussuri and Amur Districts and Corea. 

 Eubyja grisea (Warren). South Africa, 

 Aphilopota suhalhata (Warren). Orange River Colony, etc. 

 Aphilopota spissata (Warren). Natal, etc. 

 Aphilopota melanostigma (Warren). Angola, etc. 

 Aphilopota calaria (Swinhoe). British East Africa, etc. 

 Despite the fact that two of these genera are African and 

 one Asiatic, there is a direct genetic connection between them 

 of a character not unlike, although perhaps closer, than that 

 between PalcBonyssia and Nyssiodes. Undoubtedly, had 

 Phthonosema and Eubyja occurred in the same zoogeographical 

 regions, they would have been relegated to the rank of sub- 

 genera ; this fact alone is enough to stamp them indelibly as 

 members of one chain — again, a chain with one of its terminal 

 links located in Eastern Asia and thus emphasising the essen- 

 tially Asiatic nature of the subfamily. Exactly as in Biston, 

 the increased sexual dimorphism exhibited by Phthonosema 

 shows that Eubyja, in many ways, more nearly approaches 

 the common ancestor of both, which, from wing shape and 

 general structure, in addition to the extensive development of 

 the signum in the female bursa copulatrix, we judge to have 

 been sotne form leaving the Amphidasyd highway just piior 

 to the evolution of Megabisfon. 



Very early, then, preceding rather than following PalcB- 

 onyssia, the original phase of the two radiated from the Far 

 East, driving along the then more modest highlands of Central 

 Asia and thence to Persia and Arabia. Here, in place of the 

 fiery deserts of our age, it encountered the tree-clad uplands 

 of the transition period between Miocene and Pliocene times ; 

 no obstacle thus lay in its onward path. When, at length, 

 what is now the Red Sea was reached, there it found a fertile 

 river-valley, over which it crossed, passing on into Abyssinia 

 and gaining the Great Central Plateau. Once the Abyssinian 

 highlands had been attained a wide and unbroken route lay 

 open to the broad and extensive tablelands of South and 

 Central Africa to the furthest limits of which it has penetrated, 

 and persists as Eubyja grisea. 



Comparatively soon after its arrival in British East Africa, 

 from it there arose a new development in the guise of Aphilopota 

 which, even more emphatically than Eubyja, was fitted for 



Naturalist, 



