INTRODUCTION. By Dr. A. Seitz. 
and the African species are so few in number that they can be left out of account; the more so since several 
of them, such as the well-known Aletis helcita, have doubtless been modified mimetic-ally. 
In the In do-Australian region itself we may specify as particularly outstanding forms Epidesmia tri¬ 
color from the Blue Mountains (pi. I i) with its striking banded forewing and Carthaea saturnioides from West 
Australia with very large eye-spots in the centre, resembling those of an Aglia tan. In India Sarcinodes reaches 
a considerable size and shows for the most part wine-red or purple-violet shades of colour, similar to those of 
the typical Australian genus Oenochroma, which derives its name from this coloration. Common to both faunas, 
the Indian and Australian, is Eumelea, rvliich has its centre of distribution on the Malayan and Papuan is¬ 
lands. They are among the most remarkable moths known, combining with a by no means inconsiderable 
size (often even surpassing an Ourapteryx sambucaria ) a blood-red or purple colouring such as is only very 
rarely found in the whole realm of the Lepidoptera. Whilst Eumelea is distinguished from nearly all the 
Geometridae by its colour and Carthaea by its form and markings, only a few of the Oenochrominae are at all 
strongly aberrant in shape. The body indeed varies from very robust (as in the South Australian Monoctenia 
falernaria ) to the greatest imaginable slenderness ( Epidesmia hypenaria), but the wing-form keeps mostly with¬ 
in the confines of rectilinear or ordinary forms. Only a few genera, e. g. Ozola and Sarcinodes , show a ten¬ 
dency to falcation at the apex, such as is quite usual among American Geometrids, and abortion of the wings, 
such as we find in some Palaearctic and American Oenochrominae (Alsophila ), is also quite rare in the Indo- 
Australian Region. 
The second large sub-group, the Hemitheinae, embraces most of the green Geometers. They are distri¬ 
buted throughout the world, with the exception of the cold parts, but have their headquarters in the Indo- 
Australian Region and are most numerous in New Guinea. Thence over 200 species have already been recor¬ 
ded, which means, with our present incomplete knowledge of the interior of the island, that several hundreds 
of species of Hemitheinae must occur there. Some genera, mostly composed of green species only, are almost 
confined to New Guinea and the neighbouring Papuan islands, e. g. the extensive genera Prasinocyma, Ani- 
sozyga, Hypodoxa , Metallochlora, etc-., and many more widely distributed genera, such as Comibaena, Gelasma and 
Comostola, are well represented in New Guinea. Southwards the green geometers diminish, yet one could pro¬ 
bably easily make up 100 species from Australia, while New Zealand, which is otherwise not so very poor in 
Geometridae, does not appear to harbour a single Hemitheine species, the few green geometers known from 
there belonging to other groups. 
Also northward from their centre the Hemitheinae decrease rapidly. The huge area comprised in 
,,British India“ has not hitherto yielded 100 green geometers and scarcely over 150 Hemitheinae in all. Ceylon, 
with its tropical climate and luxuriant vegetation, has among almost 200 Geometrids only some three dozen 
Hemitheinae ; in the Himalayas the number rises a little again, but then sinks rapidly towards the palaearctic 
boundary; the huge Palaearctic Region has only a little over 100 species (Germany only 11). 
It must not be supposed, however, that Hemitheinae swarm in the countries which are rich in species. 
An unusually large number of Hemitheinae are among the rarer moths and this applies in a quite special degree 
to the Indo-Australian species. The infrequency of their visits to the lamp shows that most of the species 
do in fact occur sparingly, as is also the case among the European species of Hemitheinae , very few of which 
are really common. Only in their head-quarters, the Papuan or Australian subregion, can I recall excursions 
which have yielded more them a few species at one time. 
As the preceding group presents in Eumelea a quite aberrantly coloured and outstanding genus, so 
among the Indo-Australian Hemitheinae we find in the genus Dysphania a highly specialised development. Nei¬ 
ther moth nor larva gives the impression of a geometer, though the arrangement of the legs of the latter at 
once teaches us as to its affinities. Of the sharp, stout, green appearance of a Sphingid larva, but without the 
horn on the tail and with Geometric! legs, the larva of Dysphania, sits extended on the food-plant, showing 
nothing of the twig-like protective guise and striped design of most Geometrid larvae. The imagines are 
shy day-fliers, feed at flowers and, evidently avoided by birds, frequent the same bushes with Papilios, Pierids 
and Hesperids. Dysphania are absolutely confined to the Indo-Australian Region and have their centre of 
distribution on the Sunda Islands and the Moluccas; mostly yellow or sky-blue with dark spots and hyacinthine 
apex to the forewing, they are among the most striking of the geometers and may be regarded as one of the 
characteristic forms in the Indo-Australian Lepidopterous fauna as a whole. Among the subfamily Oeno¬ 
chrominae we find an analogous appearance in Celerena. which sometimes looks like a smaller edition of 
Dysphania. 
The Acidaliinae show in our region, as regards the most extensive genera, just the same inconspicuous, 
pale-coloured forms, mostly also poor in markings, which characterize this subfamily throughout the world. 
It is noteworthy that almost all the Indian representatives of this group have congeners in Europe or the 
Palaearctic Region. Besides the true Acidalia and Ptychopoda we find in India Timandra and Rhodostro- 
phia, Somatina and Problepsis. The widely distributed Indian Anisodes penetrates into the Australian subregion 
but on the other hand does not spread northwards. 
