[[p. 77]] My Dear Mr. Pascoe,

    Yours of January and March last were only received by me on my return here last month.

    Many thanks for the papers you have sent me (the list of Longicorns of Australia I have not, however, received) and especially for your ideas on the subject of publishing genera and species. Your plan has removed a considerable weight from my mind, for the quantity of minute and obscure species in my collections were beginning to frighten me.

    My collections now just packed are immense as regards specimens (above 13,000), but they are particularly poor in Longicorns and, in fact, in Coleoptera generally. There will be, no doubt, some curious and new things among the small ones, which are very numerous. They are from Ceram, Mysol, and Waigiou, and if you are taking to Homoptera you will find, I think, the largest collection of these you have ever seen.

    The Geographical distribution of Insects in the Archipelago is certainly far less strongly marked than that of Birds and Mammals, but I think that it may be in a great measure imputed to the much greater liability of insects to accidental dispersion.

    Still such cases as Tmesisternus and its allies strictly confined to the Australian region of the Archipelago, and Collyris almost equally peculiar to the Indian region, point to the same primary distribution in the one case as in the other.

    More generally, however, the same genera have, I think, subgroups with a characteristic "facies" in each region.

    Insects, moreover, are much more affected as to form by local circumstances than Birds and Mammals; thus the extreme general similarity in climate and vegetation between Borneo and N. Guinea has led also to a general similarity in the most prevalent insect forms, while the really close zoologic connection between Australia and N. Guinea is obscured by the very strongly contrasted physical features of the two countries being favourable to the propagation and development of distinct forms of insect life. Thus the ANTHRIBIDAE of the Indian region have increased and developed rapidly in the equally luxuriant forests of the Moluccas and N. Guinea, while in the arid plains of Australia they barely exist. On the other hand, the numerous MELOLONTHIDAE of Australia, favoured by the dry climate and numerous flowering shrubs of its plains, are unknown in the damp and flowerless forests of N. Guinea and the Moluccas, where also the more bulky forms of the Indian region have not been able to [[p. 78]] penetrate. Hence the excessive paucity of Lamellicorns in N. Guinea. The distribution of insects is, therefore, more obscure and complicated than that of the vertebrates. It was originally the same, but it is more rapidly affected by time and the accidents of distribution and differences of climate.

In haste,
yours very faithfully,
Alfred R. Wallace.

F. P. Pascoe Esq.