3600 Distribution of Moths of the Sub-family Bistonine. 
reached. - Simultaneously, another branch advanced up what 
was then the basin of the Hoang-ho and took possession of 
the present outposts in Western China. 
But now, climatic, conditions were more constant, and 
little further change took place in the area occupied except 
that the constant pressure of the Pacific waves and currents 
severed Japan from the mainland. This, except fer local 
changes such as that which destroyed the species in its localities 
near the old mouth of the Hoang-ho, in 1888, brings the 
vicissitudes undergone by Nyssiodes lefuarius to a close. 
VI—THE’ GENUS. P PALEONYSSIA (HARRISON). 
Paleonyssia trisecta (Warren). Distribution :—Transvaal- 
Natal, Pondoland and Transkei. 
This is the only outlying apterous form of the Bistoninae 
and, geographically, is so isolated that one feels tempted to 
state that it represents an independent development of some 
winged Bistonine genus, of the Haggardia type... This, however, 
demands an.arm of coincidence so long that one cannot grant 
it; it means that we have to assume that on three, ifnot 
four, separate occasions, the Bistonine sub; family has yielded 
wingless. forms. Nor ,is there any need of it ; structurally, 
in many respects, the insect is more primitive than Haggardia 
and its allies and it is precisely in these structures that Pale- 
onyssia approaches the older Ristonine forms. Its heavy 
antenne alone suffice to indicate an early origin and, when 
this is coupled with a furca that brings it near to Megabiston, 
a genus which has certainly produced the Lycia line and its 
satellites, the only, position possible is that it represents a very 
early offshoot from the line of which the genera. Nyssiodes, 
Nyssia and Poecilopsis are links or appendages, Its almost 
unique, stout, finger-like furca in. the male genitalia too, points 
to an origin prior to Nyssiodes and, similarly, the heavy 
antenne, not to mention other minor but primitive structural 
characters, show that, it antedates .Nyssva and . Poecilopsis. 
Thus, in it, we are concerned with the oldest apterous species 
in the chain. This simply means that, let the original home 
of the sub-family be where it may, this species has advanced 
from it. As pointed out before, of a certainty, this home was 
in North-eastern Asia, if not of the present, then that of the 
Miocene and Pliocene epochs. From this, it is clear that the 
line of descent which Palenyssia trisecta represents, has made 
a journey of ten- thousand miles from its. birth place., It 
equally implies that, if such a Journey was possible, other forms 
should have traced out the same, path, and this supposition is 
justified for such species we see in members of the genera . Actias, 
Argynnis.and Colias amongst. others. Actias_mimosae occurs 
in Natal, in,the,very,.areas occupied by P. trisecta. Of all 
Naturalist, 

