Phylogeny of the Pierine. 301 
the eucharis and aganippe forms its conspicuous character. 
I have little doubt that the curious form D. aganippe is 
one of the oldest existing species of Delias in the 
Australian region, inferring this from its retention of the 
primitive series S and M with the discoidal patch in the 
forewing in fairly distinct form, from the presence of 
yellow streaks in the interspaces of the under surface, 
and from the occurrence of a basal red spot in the pre- 
costal space of the underside of the hindwing. Many of 
these points assimilate it to the pasithoe group, and even 
more closely to D. belladonna.*  D. harpalyce and 
D. nigrina seem to follow naturally on from D. aganippe, 
though in respect of the costal red they are perhaps a little 
nearer the still more primitive D. belisama. Another 
Australian offshoot of the D. ceneus stock is probably 
represented by D. argenthona, D. mysis, D. isse, and 
D. dorimene. The Indo-Malayan and Australian nysa 
group is probably derived from the pasithoe and bella- 
donna groups through D. orphne and D. momea. It 
would be most interesting to attempt to trace in detail 
the phylogenetic history of the whole of this extensive 
genus, but it must here suffice to have indicated what ap- 
pear to be the principal lines of derivation. ‘Two points 
of analogy with the kindred neotropical genera may be 
noted before we pass on. The first is that although the 
invasion of a paler tint does in Delias tend to spht the 
original ground-colour into marginal and submarginal 
series quite similar to those of Catasticta, and though 
these series in various stages of development and sup- 
pression, as also in Catasticta, meet us here and there 
throughout the entire genus, yet in many cases the series 
never emerge in any recognizable form, and there seems 
in several species a tendency for the white mvasion to 
begin near the bases of the wings, and simply sweep the 
dark ground-colour away towards the margins. Even in 
these cases, however (as in D. belisama and D. descom- 
besi), the females, on the underside, will usually show 
some indication of the primitive series. The second 
point to be noted is the way in which the resources of 
Pierine coloration are taxed to give the insects of this 
genus a brilliant appearance. As in the case of some of 
their neotropical congeners, this is effected not so much 
* See Wallace in Trans. Ent. Soc. Lond., 3rd series, iv., p. 349. 
