Distribution of Moths of the Sub-family Bistonine. 361 
genera which are of Miocene dispersal, and are thus Miocene 
relicts, Actias keeps closest to the recognised abodes of such 
relict forms in the eastern portions of Asia and America. And, 
what is more significant, it has its headquarters now exactly 
where we have fixed the .“‘ fons et origo ”’ of the sub-family we 
are; studying... 
Obviously, a mere study of the map Gece that such 
Miocene elements of the South African..fauna would most 
-easily reach their present abodes across the continent (whether 
we cal] it Lemuria or anything, else) which once stretched 
across the Indian Ocean. But the presence of Actias selene in 
India and Ceylon, of a. modified Actias—Graellsia isabellae—in 
Spain, and. the absence of Actias from Madagascar, backed up 
by, the fact that the nearest relative of Palgonyssia in the 
latter island is Boarmia acactaria.and therefore a representative 
of a,genus flung worldwide in times far anterior to the existence 
of. Palgonyssia, precludes, this view. We glean from thése 
facts that even,then, Madagascar and consequently the African 
continent, were dsolated. from Asia via the, Indian Ocean. 
Hence the .path used must have been. southward through 
Africa and this is confirmed by the occurrence of the other 
genus Argynnis,, invoked to help us, on Mount Kilimanjaro. 
Whilst,.it is true that Argynnis hanningtonr gets no further 
south than this district, it is. well a that the fauna and 
flora of the whole of the plateau of British and (‘ former’ when 
this appears, I hope) German East Africa show affinities with 
that of South Africa on the one hand, and with that of Abyss- 
inia on the other, rather,than with. Tropical Ethiopian forms. 
From. this, we-perceive that. a passage for temperate forms 
existed—nay exists—straight down-the East African plateau 
from Abyssinia to Natal, Cape Colony and the Transvaal. 
Now add to this that the facies. of the higher Abyssinian Flora 
and Fauna is Palearctic and we get the desired connection 
with the latter geographical, region. 
To Abyssinia from ‘Western’ Asia, we have apparently the 
choice of two routes. The'course, it seems, may have been 
either’ from the Arabian plateau to that of ‘Abyssinia across 
what is now the Straits of Bab-el-Mandeb, or across the 
Isthmus of Suez, and up the Nile Valley or its eastern uplands. 
Either course postulates what is now an impossibility, and that 
is the passage of genera like ours over a desert. We have, 
however, assumed that when the advance was made, two 
passages existed, and this is certainly not justified. The present 
geological and climatic conditions, both of the hills bordering 
the Nile Basin or the East, and of the deserts of Arabia and 
Palestine, came into being with the disastrous upheavals of 
early Pliocene ‘times. Throughout the Miocene, period, these 
areas were fertile and well watered. . Where now lie the waters 
1916. Nov, 1. 

