Range of the Groups of Malayan Papilionidæ
Ornithoptera.
1. Priamus-group. Moluccas to Woodlark Island 5 species.
2. Pompeus-group. Himalayas to New Guinea, (Celebes, maximum) 11 species.
3. Brookeana-group. Sumatra and Borneo 1 species.
Papilio.
4. Nox-group. North India, Java, and Philippines 5 species
5. Coon-group. North India to Java 2 species.
6. Polydorus-group. India to New Guinea and Pacific 7 species.
7. Ulysses-group. Celebes to New Caledonia 4 species.
8. Peranthus-group. India to Timor and Moluccas (India, maximum) 9 species.
9. Memnon-group. India to Timor and Moluccas (Java, maximum) 10 species.
10. Helenus-group. Africa and India to New Guinea 11 species.
11. Pammon-group. India to Pacific and Australia 9 species.
12. Erectheus-group. Celebes to Australia 2 species.
13. Demolion-group. India to Celebes 2 species.
14. Erithonius-group. Africa, India, Australia 1 species.
15. Paradoxa-group. India to Java (Borneo, maximum) 5 species.
16. Dissimilis-group. India to Timor (India, maximum) 2 species.
17. Macareus-group. India to New Guinea 10 species.
18. Antiphates-group. Widely distributed 8 species.
19. Eurypylus-group. India to Australia 15 species.
Leptocircus.
20. Leptocircus-group. India to Celebes 4 species.
This Table shows the great affinity of the Malayan with the Indian Papilionidæ, only three out of the twenty groups ranging beyond, into Africa, Europe, or America. The limitation of groups to the Indo-Malayan or Austro-Malayan divisions of the archipelago, which is so well marked in the higher animals, is much less conspicuous in insects, but is shown in some degree by the Papilionidæ. The following groups are either almost or entirely restricted to one portion of the archipelago:—
| Indo-Malayan Region. | Austro-Malayan Region. |
| Nox-group. | Priamus-group. |
| Coon-group. | Ulysses-group. |
| Macareus-group (nearly). | Erechtheus-group. |
| Paradoxa-group. | |
| Dissimilis-group (nearly). | |
| Brookeanus-group. | |
| Leptocircus (genus). |
The remaining groups, which range over the whole archipelago, are, in many cases, insects of very powerful flight, or they frequent open places and the sea-beach, and are thus more likely to get blown from island to island. The fact that three such characteristic groups as those of Priamus, Ulysses, and Erechtheus are strictly limited to the Australian region of the archipelago, while five other groups are with equal strictness confined to the Indian region, is a strong corroboration of that division which has been founded almost entirely on the distribution of Mammalia and Birds.
If the various Malayan islands have undergone recent changes of level, and if any of them have been more closely united within the period of existing species than they are now, we may expect to find indications of such changes in community of species between islands now widely separated; while those islands which have long remained isolated would have had time to acquire peculiar forms by a slow and natural process of modification.
An examination of the relations of the species of the adjacent islands, will thus enable us to correct opinions formed from a mere consideration of their relative positions. For example, looking at a map of the archipelago, it is almost impossible to avoid the idea that Java and Sumatra have been recently united; their present proximity is so great, and they have such an obvious resemblance in their volcanic structure. Yet there can be little doubt that this opinion is erroneous, and that Sumatra has had a more recent and more intimate connexion with Borneo than it has had with Java. This is strikingly shown by the mammals of these islands—very few of the species of Java and Sumatra being identical, while a considerable number are common to Sumatra and Borneo. The birds show a somewhat similar relationship; and we shall find that the distribution of the Papilionidæ tells exactly the same tale. Thus:—
| Sumatra has 21 species | 20 sp. common to both islands; |
| Borneo has 30 species | |
| Sumatra has 21 species | 11 sp. common to both islands; |
| Java has 28 species | |
| Borneo has 30 species | 20 sp. common to both islands; |
| Java has 28 species |
showing that both Sumatra and Java have a much closer relationship to Borneo than they have to each other—a most singular and interesting result, when we consider the wide separation of Borneo from them both, and its very different structure. The evidence furnished by a single group of insects would have had but little weight on a point of such magnitude if standing alone; but coming as it does to confirm deductions drawn from whole classes of the higher animals, it must be admitted to have considerable value.
We may determine in a similar manner the relations of the different Papuan Islands to New Guinea. Of thirteen species of Papilionidæ obtained in the Aru Islands, six were also found in New Guinea, and seven not. Of nine species obtained at Waigiou, six were New Guinea, and three not. The five species found at Mysol were all New Guinea species. Mysol, therefore, has closer relations to New Guinea than the other islands; and this is corroborated by the distribution of the birds, of which I will only now give one instance. The Paradise Bird found in Mysol is the common New Guinea species, while the Aru Islands and Waigiou have each a species peculiar to themselves.
The large island of Borneo, which contains more species of Papilionidæ than any other in the archipelago, has nevertheless only three peculiar to itself; and it is quite possible, and even probable, that one of these may be found in Sumatra or Java. The last-named island has also three species peculiar to it; Sumatra has not one, and the peninsula of Malacca only two. The identity of species is even greater than in birds or in most other groups of insects, and points very strongly to a recent connexion of the whole with each other and the continent.