Thanks LJ for Memoir of Henslow; thinks it will be invaluable as an example to other clergymen.

CD is glad LJ is describing the fishes [for Zoology]; would not have permitted J. E. Gray to describe them. New species will be lithographed.

Suggests books; offers coloured drawings made by artist on Beagle voyage.

Is sorry the fish [for Zoology] give LJ so much trouble. Urges him not to give up. Describes publication plan of Zoology.

Discusses details of LJ’s part of Zoology [Fish].

CD is working hard on Coral reefs.

Informs LJ that Yarrell has recommended B. W. Hawkins to do the plates [for Fish]. Discusses arrangements to be made, number of plates, etc. Answers LJ’s questions about several specimens.

Discusses details of arrangements for descriptions and engravings [for Fish].

Details regarding Fish. CD is astonished how many new things LJ has found: "four new genera is something".

Has been unwell. Publication of two numbers [of Zoology] has been delayed. Thought first Fish number good.

Health is improved, but would do anything to get strong again. Is consulting his father; will return to London soon to see B. W. Hawkins.

Will send MS [of Fish, no. 2] to the printer, and be there when LJ comes.

Asks LJ which British birds are polygamous. His query relates to the possession by the male of secondary sexual characters.

CD is also interested in the numerical proportion of the sexes in birds.

Asks about the use of the horns in male lamellicorn or coprophagous beetles.

Thanks LJ for his useful facts. Will "look to" the reference about the nightingale.

Doctors predict it will take years for CD’s constitution to recover.

Details regarding volume on Fish.

Sends notes on Diodon.

Must give up attending Geological Society evening meetings; knocks him up.

CD is pleased with LJ’s introduction [to Fish]. He rejoices that he persuaded LJ to undertake this work.

Glad to hear that LJ will repeat his notes to Gilbert White’s [Natural history of] Selborne [1843] in a separate work.

Critical of G. R. Gray’s attaching his own name to Furnarius cunicularius [in Birds, pp. 65–6]. Strickland’s nomenclature laws are needed to check egoism.

Is sending fish skins and bottles off to Cambridge Philosophical Society.

Fish numbers [of Zoology], now finished, give CD satisfaction when he doubts whether he ought to have applied for Government money.

Wishes Thomas Bell would finish his part [Reptiles].

CD has just corrected last page of index of Coral reefs.

Asks whether LJ can throw light on this subject: "What are the checks and what the periods of life by which the increase of any given species is limited?" CD has been driven to conclude that species are mutable; allied species are co-descendants from common stocks.

On checks to increase of species and the observations which led him to regard species as mutable in form. Would welcome "at some future time" LJ’s criticism of the "sketch" of his conclusions.

Discusses checks on growth of species population; use of term "mutation" in his species theory. His belief in species mutability.

Thanks LB for his essay on local biology.

CD with much care and discomfort is now able to work a few hours almost every day.