THE AUSTRALIAN’ NATURALIST. 97 
shows us that the male is monomorphic, while the female is 
dimorphic, having two forms, one of the type of the usual 
Australian P. xgeus, and the other of the type of the male. 
In New Ireland a similar state of affairs exists, only the male 
and female are very different from those of New Britain. 
The Solomon Islands appear to be inhabited by two distinct’ 
sets of related forms agreeing with P. hecateus, in which the 
white band of the hindwing in the male extends along the 
costa to the base, or with P. ptolycus, in which this is not the 
case. In the far off Santa Cruz Islands a form, P. oberon, 
occurs. It is unfortunate that.no system of nomenclature has 
yet been devised in which the relation to the probable ancestor 
is shown, the earliest described species being taken as the 
type of the group, whereas the more typical species is more 
often described later. Taking then, in the following remarks, 
all the subspecies as of specific value, and adopting the 
centrally situated species in New Guinea as our starting point, 
we find the distribution of our group as follows :— 
_ P. ormenus, of New Guinea, is the most centrally situated 
species, and occupies in my opinion the approximate district 
in which this group originated. It has a dimorphic male, 
haying either a subapical bar on the forewing or not (othello), 
while occasionally an intermediate form (pandion) is found. 
In the female we have trimorphism, the common form 
(polydorinus) allied to the Australian female, with its extreme 
light variation (amanga) and the rarer form of the pattern of 
the male. Itappears as if the form polydorinus is the commoner 
on the mainland, while the other forms are found on the 
surrounding islands. In the Banda Islands we have a slight 
modification of ormenus, but up to the date of the publication 
of Rothschild’s Monograph only one form of female was known. 
From the Key Islands we have another modification, kevanus, 
of which the male is almogt identical with the form pandion of 
the mainland, while two forms of female occur, the common 
one and its lighter derivative. Inthe Aru Islands and Darnley 
Island we have ordinary ormenus with its females polydorinus 
and amanga ; in Australia P. xgeus, but it is only at Cape 
York that two female forms occur, and it is here that our 
species shows a strong tendency towards P. ormenus. My 
collection contains this species from Thursday Island, Cape 
York, Cooktown, Cairns, Mackay, Richmond River and Sydney. 
L also have it from Lord Howe Island, where it does not appear 
to present any modification. It has not been recorded trom 
Norfolk Island. To the westward of New Guinea we have a 
form P. inopinatus developed in Timor Laut and the neigh= 
bouring islands: 
: 1t will be noticed that this western form has 
aw tail-lke structure like so many other species. It is quite 
possible that there is yet to be found in N.W. Australia « form 
allied to thatin Timor Laut. In the Southern Moluccas we 
