│ │ │ ║ Seventy-two, Austro-Malayan Region. │ └───┴──┴───────────────────╨──────────────────────────────────────────────────┘ 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 120 species, or about the same number as I make in 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 superior 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_ Papilionidæ. Ornithoptera. 1. _Priamus_-group. Moluccas to Woodlark Island. 2. _Pompeus_-group. Himalayas to New Guinea (Celebes, maximum). 3. _Brookeana_-group. Sumatra and Borneo. Papilio. 4. _Nox_-group. North India, Java, and Philippines. 5. _Coon_-group. North India to Java. 6. _Polydorus_-group. India to New Guinea and Pacific. 7. _Ulysses_-group. Celebes to New Caledonia. 8. _Peranthus_-group. India to Timor and Moluccas (India, max.). 9. _Memnon_-group. India to Timor and Moluccas (Java, max.). 10. _Helenus_-group. Africa and India to New Guinea.