SIRE:—Allow me to give your Majesty a rapid sketch of the most interesting facts observed by me since leaving Rio. The first thing which struck me on arriving at Bahia was the presence of the erratic soil, corresponding to that of Tijuca and the southern part of Minas-Geräes, which I have visited. Here, as there, this soil, identical in its constitution, rests upon rocks in place, of the most diversified character. I have found it also at Maceió, at Pernambuco, at Parahyba do Norte, at Ceará, at Maranham, and at Pará. This is a fact, then, established on the largest scale. It shows that the superficial materials which, here as in the North of Europe and America, may be designated as drift, cannot be the result of the decomposition of underlying rocks, since the latter are sometimes granite, sometimes gneiss, sometimes mica or talcose slate, sometimes sandstone, while the drift presents the same composition everywhere. I am as far as ever from being able to point out the origin of these materials and the direction of their transportation. Now that Major Coutinho has learned to distinguish the drift from the decomposed rocks, he assures me that we shall find it throughout the valley of the Amazons. The boldest imagination shrinks from any generalization on this subject, and yet we must gradually familiarize ourselves with the idea that the cause which has dispersed these materials, whatever it be, has acted on the largest scale, since they are probably to be found all over the continent. Already I learn that my young travelling companions have observed the drift in the environs of Barbacena and Ouro-Preto, and in the valley of the Rio das Velhas. My zoölogical results are not less satisfactory; and to speak of the fishes alone, I have found at Pará during one week more species than have as yet been described from the whole basin of the Amazons,—sixty-three in all. This study will be useful, I hope, to ichthyology, for I have already succeeded in distinguishing five new families and eighteen new genera, while the unpublished species do not number less than forty-nine. It is a guaranty of the rich harvest I shall make when I enter upon the domain of the Amazons properly so called; for I have seen as yet but a tenth part of the fluviatile species known from this basin, and some of the marine species which come up to Pará. Unhappily, Mr. Burkhardt is ill, and has been able to paint but four of the new species we have procured; and of nearly half the number, only single specimens have been secured. On my return I must make a longer stay in Pará in order to fill these deficiencies. I am enchanted with the grandeur of nature here. Your Majesty certainly reigns over the most beautiful empire of the world; and, personal as are the attentions which I receive wherever I stop, I cannot but believe that, were it not for the