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subjects were then uppermost in my mind. The first from which I will quote is that to Mr. Bates, and referring to a paper on the Papilios of the Amazon which he had sent me I make some remarks on the distribution of animals in South America, which I do not think I have published anywhere. “Your paper is in every respect an admirable one, and proves the necessity of minute and exact observation over a wide extent of country to enable a man to grapple with the more difficult groups, unravel their synonymy, and mark out the limits of the several species and varieties. All this you have done, and have, besides, established a very interesting fact in zoological geography, that of the southern bank of the lower river having received its fauna from Guayana, and not from Brazil. There is, however, another fact, I think, of equal interest and importance which you have barely touched upon, and yet I think your own materials in this very paper establish it, viz. that the river, in a great many cases, limits the range of species or of well-marked varieties. This fact I considered was proved by the imperfect materials I brought home, both as regards the Amazon and Rio Negro. In a paper I read on ‘The Monkeys of the Lower Amazon and Rio Negro' I showed that the species were often different on the opposite sides of the river. Guayana species came up to the east bank, Columbian species to the west bank, and I stated that it was therefore important that travellers collecting on the banks of large rivers should note from which side every specimen came. Upon this Dr. Gray came down upon me with a regular floorer. “Why,’ said he, “we have specimens collected by Mr. Wallace himself marked “Rio Negro” only.' I do not think I answered him properly at the time, that those specimens were sent from Barra before I had the slightest idea myself that the species were different on the two banks. In mammals the fact was not so much to be wondered at, but few persons would credit that it would apply also to birds and winged insects. Yet I am convinced it does, and I only regret that I had not collected and studied birds there with the same assiduity as I have here, as I am sure they would furnish some most interesting results. Now, it seems to me that a person having no special knowledge of the district would have no idea from your paper that the species did not in almost every instance occur on both banks of the river. In only one case do you specially mention a species being found only on the north bank. In other cases, except where the insect is local and confined to one small district, no one can tell whether they occur on one or both banks. Obydos you only mention once, Barra and the Tunantins not at all. I think a list of the species or varieties occurring on the south bank or north bank only should have been given, and would be of much interest as establishing the fact that large rivers do act as limits in determining the range of species. From the localities you give, it appears that of the sixteen species of papilio peculiar to the Amazon, fourteen occur only on the south bank; also, that the Guayana species all pass to the south bank. These facts I have picked out. They are not stated by you. It would seem, therefore, that Guayana forms, having once crossed the river, have a great tendency to become modified, and then never recross. Why the Brazilian species should not first have taken possession of their own side of the river is a mystery. I should be inclined to think that the present river bed is comparatively new, and that the southern lowlands were once continuous with Guayana; in fact, that Guayana is older than north Brazil, and that after it had pushed out its alluvial plains into what is now north Brazil, an elevation on the Brazilian side made the river cut a new channel to the northward, leaving the Guayana species isolated, exposed to competition with a new set of species from further south, and so becoming modified, as we now find them. . . . The whole district is, I fear, too little known geologically to test this supposition. The mountains of north Brazil are, however, said to be of the cretaceous period, and if so their elevation must have occurred in tertiary times, and may have continued to a comparatively recent period. Now if there are no proofs of such recent upheaval in the southern mountains of Guayana, the theory would thus far receive support. I regret that your time was not more equally divided between the north and south banks, but I suppose you found the south so much more productive in new and fine things. . . . “I am here making what I intend to be my last collections, but am doing very little in insects, as it is the wet season and all seems dead. I find in those districts where the seasons are strongly contrasted the good collecting time is very limited—only about a month or two at the beginning of the dry, and a few weeks at the commencement of the rains. It is now two years since I have been able to get any beetles, owing to bad localities and bad weather, so I am becoming disgusted. When I do find a good place it is generally very good, but such are dreadfully scarce. In Java I had to go forty miles in the eastern part and sixty miles in the western to reach a bit of forest, and then I got scarcely anything. Here I had to come a hundred miles inland, by Palembang, and though in the very centre of Eastern Sumatra, the forest is only in patches, and it is the height of the rains, so I get nothing. A longicorn is a rarity, and I suppose I shall not have as many species in two months as I have obtained in three or four days in a really good locality... I am getting, however, some sweet little blue butterflies (Lycaenidae), which is the only thing that keeps up my spirits.”
The letter to my friend Silk will be, perhaps, a little more amusing, and perhaps not less instructive.
“Lobo Roman, Sumatra, December 22, 1861.
“MY DEAR GEORGE,
“Between eight and nine years ago, when we were concocting that absurd book, ‘Travels on the Amazon and Rio Negro,' you gave me this identical piece of waste paper with sundry others, and now having scribbled away my last sheet of “hot-pressed writing,' and being just sixty miles from another, I send you back your gift, with interest; so you see that a good action, sooner or later, find its sure reward.
“I now write you a letter, I hope for the last time, for I trust our future letters may be vivá voce, as an Irishman would say, while our epistolary correspondence will be confined to notes. I really do now think and believe that I am coming home, and as I am quite uncertain when I may be able to send you this letter, I may possibly arrive not very long after it. Some fine morning I expect to walk into 79, Pall Mall, and shall, I suppose, find things just the same as if I had walked out yesterday and come in to-morrow ! There will you be seated on the same chair, at the same table, surrounded by the same account books, and writing upon paper of the same size and colour as when I last beheld you. I shall find your inkstand, pens, and pencils in the same places, and in the same beautiful order, which my idiosyncrasy compels me to admire, but forbids me to imitate. (Could you see the table at which I am now writing, your hair would stand on end at the reckless confusion it exhibits 1) I suppose you have now added a few more secretaryships to your former multifarious duties. I suppose that you still walk every morning from Kensington and back in the evening, and that things at the archdeacon's go on precisely and identically as they did eight years ago." I feel almost inclined to parody the words of Cicero, and to ask indignantly, “How long, O Georgius, will you thus abuse our patience? How long will this sublime indifference last 2' But I fear the stern despot, habit, has too strongly riveted your chains, and as, after many years of torture the Indian fanatic can at last sleep only on his bed of spikes, so perhaps now you would hardly care to change that daily routine, even if the opportunity were thrust upon you. Excuse me, my dear George, if I express myself too strongly on this subject, which is truly no business of mine, but I cannot see, without regret, my earliest friend devote himself so entirely, mind and body, to the service of others.
“I am here in one of the places unknown to the Royal Geographical Society, situated in the very centre of East Sumatra, about one hundred miles from the sea in three directions. It is the height of the wet season, and the rain pours down strong and steady, generally all night and half the day. Bad times for me, but I walk out regularly three or four hours every day, picking up what I can, and generally getting some little new or rare or beautiful thing to reward me. This is the land of the two-horned rhinoceros, the elephant, the tiger, and the tapir; but they all make themselves very scarce, and beyond their tracks and their dung, and once hearing a rhinoceros bark not far off, I am not aware of their existence. This, too, is the very land of monkeys; they swarm about the villages and plantations, long-tailed and short-tailed, and with no tail at all, white, black, and grey; they are eternally racing about the tree-tops, and gambolling in the most amusing manner. The way they jump is amazing. They throw themselves recklessly through the air, apparently sure, with one or other of their four hands, to catch hold of something. I estimated one jump by a long-tailed white monkey at thirty feet horizontal, and sixty feet vertical, from a high tree on to a lower one ; he fell through, however, so great was his impetus, on to a lower branch, and then, without a moment's stop, scampered away from tree to tree, evidently quite pleased with his own pluck. When I startle a band, and one leader takes a leap like this, it is amusing to watch the others—some afraid and hesitating on the brink till at last they pluck up courage, take a run at it, and often roll over in the air with their desperate efforts. Then there are the long-armed apes, who never walk or run upon the trees, but travel altogether by their long arms, swinging themselves from bough to bough in the easiest and most graceful manner possible. “But I must leave the monkeys and turn to the men, who will interest you more, though there is nothing very remarkable in them. They are Malays, speaking a curious, halfunintelligible Malay dialect—Mohammedans, but retaining many pagan customs and superstitions. They are very ignorant, very lazy, and live almost absolutely on rice alone, thriving upon it, however, just as the Irish do, or did, upon
* Mr. Silk was private secretary and reader to the then Archdeacon Sinclair, Vicar of Kensington.