Galapagos land birds and reptiles.

No two naturalists agree on any fundamental idea [of species]. "Everything is arbitrary."

Has been with Richard Owen going over the S. American fossils.

Has worked out the non-relation between animals’ bulk and luxuriance of vegetation.

The horse once common on the Pampas. The mystery of the extinction of these animals.

Responds to Lyell’s query [missing] about northern and southern limits of coral islands of the Pacific. Warns that coral islands are much more thinly distributed than people realise and cites examples. Comments on views of Matthew Flinders. Reading work of É[lie] de B[eaumont]. Notes difficulty of setting an east-west boundary to coral islands.

Comments on receiving copy of Lyell’s Elements [of geology]. Much is new to CD, and he is copying out notes and references.

Criticises geological work of John Phillips.

Describes expedition to Glen Roy, about which he is writing a paper ["Parallel roads of Glen Roy" (1839), Collected papers 1: 87–137].

Enjoys the Athenaeum Club.

Criticises entomological work of F. W. Hope.

Asks Lyell to obtain for him a copy of barometric readings made at Leith.

Asks him to ascertain altitude of several Scottish lochs.

Comments on FitzRoy’s character.

Comments on an article in Edinburgh Review [by David Brewster, 67 (1838): 271–308] on Comte’s Philosophie positive.

Discusses falsity of Élie de Beaumont’s views of contemporaneous parallel lines of elevation and subsidence.

Owen’s views of relationship of reptiles to birds.

On "question of species" CD has filled notebook after notebook with facts, "which begin to group themselves clearly under sub-laws".

Announces his engagement to Emma Wedgwood.

Discusses his Glen Roy paper [(1839), Collected papers 1: 87–137], which he is sending to CL.

Remarks on Charles MacLaren’s treatment of alluvium. Comments on alluvial action in Lochaber.

Remarks on his illness and treatment.

Discusses MS [of Coral reefs] and changes in his view of coral reefs since Journal of researches. Mentions C. G. Ehrenberg’s observations on coral reefs.

Answers a number of queries from Lyell concerning geography and geology of Chiloé Island and its relationship to the Cordilleras.

Asks about "perched rocks" on Jura and notes their relevance to Louis Agassiz’s theory. Discusses Agassiz’s view on Jura.

Mentions seeing Robert Brown.

Notes R. I. Murchison’s discovery of shells in central England.

Weakness of negative evidence.

Discusses the role of ice in determining the geological features of the Jura. Mentions view of Agassiz. Objects to idea of "a [sea of ice] carrying rocks". Notes Agassiz’s earlier view of "ice expanded in the line of the Great Swiss Valley". Comments on Pentlands.

Defends his theory [in "Parallel roads of Glen Roy" (1839), Collected papers 1: 87–137] against the view that the "roads" were formed by glacial action.

Discusses at length Louis Agassiz’s book [Études sur les glaciers (1840)] and Agassiz’s explanation of moraines. Defends his own theory of the importance of floating ice. Relates glacier theory to his own interpretation of Glen Roy.

Mentions a paper he is writing on South American boulders and till [Collected papers 1: 145–63].

Discusses various types of coral reefs on which he has been collecting notes. Views of C. G. Ehrenberg. His conception of the formation of Bermuda.

Pessimistic about the effect of his poor health on his scientific work.

Discusses relationship of subsidence to the formation of coral reefs.

Discusses growth of various species of coral. Explains significance of dead reefs.

Describes meeting of the Council of the Geological Society; the controversy involving Edward Charlesworth.

Mentions conversations with William Lonsdale about Lonsdale’s work on corals and the financial support for his work.

Murchison’s views on glaciation in Wales.

Agassiz’s observations at Glen Roy.

Believes "absurd letter" hastily read at last Geological Society Council meeting was from Charlesworth’s solicitor. Suggests that it may have been sent to entrap the Council and that it should be read over carefully.

Mentions expected birth of child [Henrietta Emma].

BAAS meeting.

Comments on letters from G. R. Waterhouse and William Lonsdale.

Describes survival of apparently "fossil" seeds sent by W. Kemp.

Is at work on MS [of Volcanic islands].

Description and defence of his view of the tosca in Banda Oriental, along the Rio Uruguay and at the Rio Negro, taking issue with A. D. d’Orbigny. Refers to the pumice in the Patagonian Territory. Two tables show the layered tosca formation along the Uruguay.

Asks about CL’s new book [Travels in North America (1845)].

Discusses views of A. D. d’Orbigny on elevation.

Mentions reading W. H. Prescott [History of the conquest of Mexico (1843)].

Remarks on fossils described in A. D. d’Orbigny’s Voyage dans l’Amérique méridionale.

Asks CL whether he has talked with John Murray concerning 2d ed. [of Journal of researches].

Mentions conversation with Hugh Cuming about South American shells. Has had G. B. Sowerby (elder) look at some specimens.

Sends the first part of Journal of researches [2d ed.]. Explains his dedication of book to CL. Describes revisions.

Has received CL’s book [Travels in North America, 2 vols. (1845)].