Dear Sir

Owing to your letter of January the 4^th. being addressed to London I received it only yesterday. I assure you that I am greatly pleased at the honour which you intend to confer on me by dedicating your new work to me.² You seem to have had a most interesting expedition, & I am very glad that you intend to publish a general account of the results.³

Your discovery of marine shells high up the Amazons possesses extreme interest, not only in itself, but as one more most striking instance how rash it is to assert that any deposit is not a marine formation because it does not contain fossils. Agassiz will not at all approve of this discovery; & if I am not mistaken marine shells have also been found in the large island at the mouth of the river. As for myself I never believed for a moment in Agassiz’s idea of the origin of the Amazonian formation.⁴

I shall be very curious to read a full account of the wingless grebe-like bird which you have discovered, & of the great deposit of bones; but I fear of the latter you will not have been able to bring away many specimens.⁵

With my very sincere thanks for the intended honour & for your kind letter, I remain | Dear Sir, | yours very faithfully | Charles Darwin