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Darwin Correspondence Project

To ?   31 December [1852–3]1

Down Bromley Kent

Dec. 31st

My dear Sir

It would give me real pleasure to assist you in any, the slightest, manner. The Coquimbo beds are described in my “Geological observations on S. America” p. 128— There were altogether 24 shells in the Carcharias bed,2 of which Mr Sowerby3 cd. not distinguish a Artemis & great Mytilus from recent species; & I feel sure that Balanus psittacus4 is recent, & I conclude that B. Coquimbensis is only a variety of another recent species, viz. B. lævis.5 There is much difficulty in deciding on age of the isolated Tertiary deposits on coast of Chile; the most probable conclusion seems to be that they are old Miocene or Eocene.— The generic character, I believe, is Miocene, but nearly all the species are distinct, & all according to M. d’Orbigny.—6

If you think it worth while you will see in work referred to, which is at Geolog. Soc, what little I have said on this subject.—

I shd. add that M. d’Orbigny does not agree with Mr Sowerby that the Artemis & Mytilus are recent species.—7

My dear Sir | Yours very sincerely | C. Darwin


Dated on the assumption that CD wrote the letter before publishing Living Cirripedia (1854), to which he does not refer. He had recommenced working on Balanus late in 1852 (see ‘Journal’; Correspondence vol. 5, Appendix I).
The Tertiary bed at Herradura Bay, Chile, characterised by the great numbers of bones of Cetacea and sharks teeth ‘closely resembling those of the Carcharias megalodon.’ (South America, pp. 128–9).
George Brettingham Sowerby had described CD’s collection of fossil shells for South America.
See Living Cirripedia (1854): 207–8. CD stated that he had seen one specimen attached to Mytilus magellanicus.
See Living Cirripedia (1854): 227–8.
Alcide Charles Victor Dessalines d’Orbigny had also examined CD’s South American fossil shells (South America, p. iv). See Correspondence vol. 3.
See Correspondence vol. 3, letter from A. C. V. D. d’Orbigny, 14 February 1845, and n. 5.


Responds to correspondent’s request for information about shells from the Coquimbo beds in Chile. Difficulty in deciding on age of deposits and species. Notes views of Alcide d’Orbigny.

Letter details

Letter no.
Charles Robert Darwin
Sent from
Source of text
Houghton Library, Harvard University
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 13872,” accessed on 24 August 2019,

Also published in The Correspondence of Charles Darwin, vol. 5