Sends his paper ["Insect fauna of the Amazon valley", Trans. R. Entomol. Soc. Lond. 2d ser. 5 (1861): 223–8, 335–61].

Points out three areas of interest arising from the study of the species of Papilio: the derivation of the fauna, the variability of the species, and the permanence of local varieties.

Discusses J. S. Baly’s views on specific differences in reproductive organs [Catalogue of the Hispidae in the collection of the British Museum (1858)].

Comments on the great extent of variations and on the acknowledgment of the new idea of greater female variety.

Expresses belief that the glacial period did affect the tropics, though HWB’s arguments have confounded him.

Poses a series of questions concerning sexual selection.

Discusses specific varieties, especially geographic varieties.

Comments on the effects of the glacial age on the tropics.

Sexual selection.

CD urges HWB to write on his travels;

asks for facts on domestic variations;

is pleased by HWB’s acceptance of the theory of sexual selection.

He still believes in migration from north to south during glacial age.

Hopes Bates will publish a paper on mimicry.

Mention of Volucella.

Recommends publisher for HWB; admires J. van Voorst but suggests Murray.

In reply to HWB’s letter [missing], comments on neuters and mimicry.

Discusses the mimicry of the Volucella flies, and the bees and wasps they mimic. Compares it with the different object of mimicry in butterflies.

Refers to incompleteness of Cuthbert Collingwood’s paper [? "On homophormism, or organic representative forms", Proc. Liverpool Lit. & Philos. Soc. 14 (1860): 181–216].

Thanks CD for help in selecting a publisher for his book [The naturalist on the river Amazons (1863)].

Thanks HWB for information on Volucella, although he does not know when he will use it.

Is glad HWB is beginning his book.

CD is beginning work on his orchid book.

Furnishes CD with more information on Volucella and gives him references relating to this and butterfly colourings. States that colours are not necessarily related to resting-places but rather an endowment to enable them to withstand adverse conditions.

Thanks HWB for references.

Praises his paper ["Contributions to an insect fauna of the Amazon valley", read before Linnean Society, 21 Nov 1861, Trans. Linn. Soc. Lond. 23 (1862) : 495–566] which solves "one of the most perplexing problems which could be given to solve".

Discusses the difficulties of writing and expresses disappointment at Wallace’s book [Travels on the Amazon (1861)].

Praises MS of first chapter of HWB’s book [The naturalist on the river Amazons (1863)]. Suggests he give common names and make comparisons to familiar English species to help readers. Suggests a few changes. Will speak strongly to Murray about publishing whenever HWB is ready.