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Darwin Correspondence Project

To J. D. Hooker   21 February [1870]1

Down. | Beckenham | Kent. S.E.

Feb. 21

My dear Hooker

I read yesterday the Notes on Round Isld. which I owe to you.—2 Was there ever such an enigma? If in the course of a week or two you can find time to let me hear what you think, I shd. very much like to hear. Or we hope to be at Erasmus on March 4th for a week;3 would there be any chance of your coming to Luncheon then? What a case it is.— Palms, Screw-Pines, 4 snakes, not one living on main island, Lizards, insects & not one Land Bird. But above everything such a proportion of individual monocotyledons! The conditions do not seem very different from the tuff Galapagos isld;4 but as far as I remember very few monocotyledons there. Then again the isld seems to have been elevated. I wonder much whether it stands out in the line of any oceanic current, which does not so forcibly strike the main island?

But why, oh why, shd so many cotyledons have come there; or why shd. they have survived there more than on main island, if once connected?5 So again I cannot conceive that 4 snakes shd have become extinct in Mauritius & survived on Round Island. For a moment I thought that the Mauritius might be the newer island; but the enormous degradation which the outer ring of rocks has undergone flatly contradicts this; & the marine remains on summit of Round Isld. indicates the isld to be comparatively new; unless indeed they are fossil & extinct marine remains.—6 Do tell me what you think. There never was such an enigma.— I rather lean to separate immigration, with of course subsequent modification; some forms, of course, also coming from Mauritius. Speaking of Mauritius, reminds me that I was so much pleased day before yesterday by reading a review of book on Geology of St. Helena, by officer who knew nothing of my hurried observations, but confirms nearly all that I have said on general structure of the Islands & on its marvellous denudation.7 The Geology of that island was like a novel.—

Yours affectionately | C. Darwin


The year is established by the reference to Henry Barkly’s ‘Notes on the flora and fauna of Round Island’ (see n. 2, below).
Hooker had evidently sent CD proof-sheets of Barkly’s ‘Notes on the flora and fauna of Round Island’. The essay was read at a meeting of the Royal Society of Arts and Sciences of Mauritius on 30 December 1869 and published in the Mauritius almanac and colonial register for 1870 (Barkly 1870). The proof-sheets, corrected by Barkly and annotated by CD, are in the Darwin Pamphlet Collection–CUL. See also Correspondence vol. 17, enclosure to letter from J. D. Hooker to Emma Darwin, 29 March 1869.
The Darwins stayed with Erasmus Alvey Darwin from 5 March to 12 March 1870 (Emma Darwin’s diary (DAR 242)).
Round Island, like the Galápagos Islands, is volcanic.
Barkly noted that the ratio of monocotyledons to dicotyledons on Round Island was 12 to 14, the established norms in the tropics being 1 to 5 (Barkly 1870, p. 95).
Barkly had found madrepores (a type of coral) on the summit of Round Island (Barkly 1870, p. 101).
CD refers to The geology of St Helena, by John Ryder Oliver (Oliver 1869); the review has not been identified. CD discussed St Helena in chapter 4 of Volcanic islands.


Barkly, Henry. 1870. Notes on the flora and fauna of Round Island. In The Mauritius almanac and colonial register for 1870. Edited by John B. Kyshe. Mauritius: [n.p.].

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

Oliver, John R. 1869. The geology of St Helena. St Helena: Benjamin Grant.


Has read the notes on Rond [Round] Island which he owes to JDH. What an enigma its flora and fauna present, especially the problem of monocotyledons! Asks JDH’s opinion.

A new book on St Helena confirms CD’s observations.

Letter details

Letter no.
Charles Robert Darwin
Joseph Dalton Hooker
Sent from
Source of text
DAR 94: 164–6
Physical description
ALS 5pp

Please cite as

Darwin Correspondence Project, “Letter no. 7115,” accessed on 3 June 2023,

Also published in The Correspondence of Charles Darwin, vol. 18