Asks THH’s opinion on embryological views of G. A. Brullé [Ann. & Mag. Nat. Hist. 13 (1844): 484–6] and F. M. Barnéoud [Ann. des Sci. Nat. ser. 3, Bot. 6 (1846): 268–96] and on Milne-Edwards’ classification.

Has been reading John Goodsir ["On the morphological constitution of the skeleton of the vertebrate head", Edinburgh New Philos. J. 2d ser. 5 (1857): 123–78].

Has embryology of bats ever been worked out?

THH comments on G. A. Brullé’s paper ["Researches upon the transformations of the appendages of the Articulata", Ann. & Mag. Nat. Hist. 13 (1844): 484–6].

Thanks THH for his cautionary response on Brullé, but departs from THH in thinking that Barnéoud, if true, would shed light on Milne-Edwards’ proposition that the wider apart classes of animals are the earlier they depart from common embryonic plan.

Thanks for three last lectures and the account of cirripedes.

Difficulty of classifying the higher groups.

Agassiz’s superficiality and wretched reasoning powers. But he stirred up Europe on glaciers. Lyell has been working on their effects – testing work of others.

CD believes "Natural Systems" ought to be simply genealogical. "Time will come when we shall have true genealogical trees of each great kingdom of nature."

On classification and possibilities of a scientific morphology and zoology. CD’s "pedigree business" is important for physiology but has nothing to do with pure zoology any more than human pedigree has to do with the census. Zoological classification is a census of the animal world.

Thinks naturalists look for something further than Cuvier’s view of classification. Poses a theoretical problem on the classification of the races of man to prove that a genealogical system is best.

Glad THH has taken up aphid question versus Owen ["On the agamic reproduction and morphology of Aphis", Trans. Linn. Soc. Lond. 22 (1858): 193–236].

Fertilisation and inheritance discussed. Speculates that fertilisation may be a mixture rather than a fusion. Can understand in no other way why crossed forms tend to go back to ancestral forms.

THH’s catalogue [THH and R. Etheridge, A catalogue of the collection of fossils in the Museum of Practical Geology (1865), part published in 1857] best résumé he has seen of science of natural history. On classification he is not quite sure that he wholly goes along with THH. Encloses a few criticisms of THH’s preface.[enclosure survives as copy only].

Congratulations on birth of THH’s daughter [Jessie].

On aboriginal dun colour of horses.

Examples of inaccuracies and perpetuation of errors [on hybrids] by "compilers, of which I am one".

CD’s reasons for not signing the memorial requesting removal of natural history exhibits from British Museum. Less sure about moving botanical specimens to Kew. His notion of museum organisation.

Hooker has convinced him that move of British Museum by Government is anticipated. He is now willing to sign the memorial. Still fears for library needs, and objects to distant Kensington site. Lyell should be asked to sign.

Has had some misgivings about the memorial but now thinks his fears were vain and cowardly. Regrets R. I. Murchison was not told in advance. His low opinion of the Government and B. Disraeli.

K. E. von Baer’s view of the air bladder of fishes.

Sends THH questions about "serial homologies" and "vegetative repetition" in Mollusca and Radiata.

Abstract volume [Origin] nearly completed.

Serial homologies in the Mollusca. Gives instances of repetition of homological parts in Radiata.

Thanks for THH’s examples of serially modified and homologous parts in Radiata. Cannot understand how he forgot such cases.

Agassiz’s Essay on classification [1859] utterly impracticable rubbish.

THH should understand that CD’s hypothesis [natural selection] has as many flaws and holes as sound parts. The question is whether CD’s rag of a hypothesis is worth anything. A poor rag is better than nothing to carry one’s fruit to market.

Extended discussion of their respective difficulties with the definition and status of species and with the extent to which the theory of transmutation may be applied.

Has rediscovered S. S. Haldeman’s 1844 paper defending the transmutation theory with great skill.

Asks for reference to Geoffroy Saint-Hilaire’s first enunciation of the progressive development and transmutation theory.

Origin is finished.

Asks for names of foreign speculative naturalists.

Hopes THH will think he is on right road despite errors.