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Section D contains the strongest-bodied and most swift-flying of the genus. They love sunlight, and frequent the borders of streams and the edges of puddles, where they gather together in swarms consisting of several species, greedily sucking up the moisture, and, when disturbed, circling round in the air, or flying high and with great strength and rapidity.
Geographical Distribution.-One hundred and thirty species of Malayan Papilionidæ are now known within the district extending from the Malay peninsula, on the north-west, to Woodlark Island, near New Guinea, on the south-east.
The exceeding richness of the Malayan region in these fine insects is seen by comparing the number of species found in the different tropical regions of the earth. From all Africa only 33 species of Papilio are known; but as several are still undescribed in collections, we may raise their number to about 40. In all tropical Asia there are at present described only 65 species, and I have seen in collections but two or three which have not yet been named. In South America, south of Panama, there are 150 species, or about oneseventh more than are yet known from the Malayan region; but the area of the two countries is very different; for while South America (even excluding Patagonia) contains 5,000,000 square miles, a line encircling the whole of the Malayan islands would only include an area of 2,700,000 square miles, of which the land-area would be about 1,000,000 square miles. This superior
richness is partly real and partly apparent. The breaking up of a district into small isolated portions, as in an archipelago, seems highly favourable to the segregation and perpetuation of local peculiarities in certain groups ; so that a species which on a continent might have a wide range, and whose local forms, if any, would be so connected together that it would be impossible to separate them, may become by isolation reduced to a number of such clearly defined and constant forms that we are obliged to count them as species. From this point of view, therefore, the greater proportionate number of Malayan species may be considered as apparent only. Its true superiority is shown, on the other hand, by the possession of three genera and twenty groups of Papilionidæ against a single genus and eight groups in South America, and also by the much greater average size of the Malayan species. In most other families, however, the reverse is the case, the South American Nymphalidæ, Satyridæ, and Erycinidæ far surpassing those of the East in number, variety, and beauty.
The following list, exhibiting the range and distribution of each group, will enable us to study more easily their internal and external relations.
Range of the Groups of Malayan Papilionida. Ornithoptera. 1. Priamus - group. Moluccas to Woodlark
Island ... ... ... ... ... ... 5 species. 2. Pompeus - group. Himalayas to New
Guinea, (Celebes, maximum) ... ... 11
pines ... ... ... ... .. ... 5 species.
and Pacific ... ... ... ... ... 7
Moluccas (India, maximum) ... ... 9
luccas (Java, maximum) ... ... ... 10. Helenus-group. Africa and India to New
Guinea ... ... ... ... ... 11
tralia ... ... ... ... ... ...
maximum. ... ... ... ... ... 5
maximum) ... ... ... ... ... 17. Macareus-group. India to New Guinea ... 18. Antiphates-group. Widely distributed ...
19. Eurypylus-group. India to Australia ... Leptocircus.
20 Leptocircus-group. India to Celebes ... 4 ,
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 IndoMalayan 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.
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 seabeach, 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 thein 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 naturai 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 Papilionida tells exactly the same tale. Thus:
Sumatra has... 21 species
20 sp. common to both islands; Sumatra Java
11 sp. common to both islands ; Borneo ,
} 20 sp. common to both islands ; Java „ ...
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