Touching at the Abrolhos, we arrived here on April 4th, when amongst others I received your most kind letter. You may rely on it during the evening I thought of the many most happy hours I have spent with you in Cambridge. I am now living at Botofogo, a village about a league from the city, and shall be able to remain a month longer. The "Beagle" has gone back to Bahia, and will pick me up on its return. There is a most important error in the longitude of South America, to settle which this second trip has been undertaken. Our chronometers, at least sixteen of them, are going superbly; none on record have ever gone at all like them. A few days after arriving I started on an expedition of 150 miles to Rio Macao, which lasted eighteen days. Here I first saw a tropical forest in all its sublime grander--nothing but the reality can give any idea how wonderful, how magnificent the scene is. If I was to specify any one thing I should give the pre-eminence to the host of parasitical plants. Your engraving is exactly true, but underrates rather than exaggerates the luxuriance. I never experienced such intense delight. I formerly admired Humboldt, I now almost adore him; he alone gives any notion of the feelings which are raised in the mind on first entering the Tropics. I am now collecting fresh-water and land animals; if what was told me in London is true, viz., that there are no small insects in the collections from the Tropics, I tell Entomologists to look out and have their pens ready for describing. I have taken as minute (if not more so) as in England, Hydropori, Hygroti, Hydrobii, Pselaphi, Staphylini, Curculio, etc. etc. It is exceedingly interesting observing the difference of genera and species from those which I know, it is however much less than I had expected. I am at present red-hot with spiders; they are very interesting, and if I am not mistaken I have already taken some new genera. I shall have a large box to send very soon to Cambridge, and with that I will mention some more natural history particulars. The Captain does everything in his power to assist me, and we get on very well, but I thank my better fortune he has not made me a renegade to Whig principles. I would not be a Tory, if it was merely on account of their cold hearts about that scandal to Christian nations--Slavery. I am very good friends with all the officers. I have just returned from a walk, and as a specimen, how little the insects are known. Noterus, according to the 'Dictionary Classique,' contains solely three European species. I in one haul of my net took five distinct species; is this not quite extraordinary?...