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To William Henry Benson   7 December [1855]1

Down Bromley Kent.

Dec: 7th

My dear Sir,

I thank you cordially for the very kind manner with which you have answered my note,2 & for the very great trouble you have taken in answering it so fully & so very clearly.

The facts which you give are the very thing which I wanted.

The range of shells over the land seems to me in many cases much more confined than plants: on the other hand what a curious case that of Madeira & St Helena shells!3 I collected several semi-fossil shells at St Helena, which were described by Mr Sowerby:4 I cannot remember whether any are left, but if they would interest you I would look: I know I gave away many but forget whether I gave all. I am particularly obliged to you for mentioning the case of Bulimus Bengalensis, which is so curious; I am very glad to hear of it, for it is so exactly parallel to what, as is so well known, sometimes occurs with plants.— I presume such cases are not common with land Mollusca.5 The whole subject of the distribution of pulmoniferous6 Mollusca seems to me very interesting. Am I not right in believing that many fresh-water species have very wide ranges?7 Though I ask this, I am not so unreasonable as to expect you again to take the trouble to answer me in full.8

Thank you much for saying that you will keep in mind my very strong wish for information in regard to distribution of alpine or semi-alpine shells.

You kindly enquire about my health: though I appear a strong man, I am far from being so, & shall never be so again; but I contrive to do some Nat. History work every day in my life.

Dr Gully did me much good.9

I sincerely hope that you profited by the water cure, & are now stronger.—

With many thanks pray believe me in haste | yours sincerely | CH. Darwin

Copy

1
The year is established by the relationship between this letter and the memorandum from W. H. Benson, 5 December 1855 (see Correspondence vol. 5).
2
CD refers to an earlier letter to Benson that has not been found, and to the memorandum from W. H. Benson, 5 December 1855 (Correspondence vol. 5). CD had asked Benson whether any alpine shells were common to the heights of Ceylon (now Sri Lanka) and India (see Correspondence vol. 5, letter to E. L. Layard, 9 December 1855).
3
See Correspondence vol. 5, memorandum from W. H. Benson, 5 December 1855 and n. 14. See also Origin, p. 391.
4
See Journal of researches, p. 582; see also p. 426. George Brettingham Sowerby described extinct land-shells from St Helena in the appendix to Volcanic islands, pp. 155–8.
5
Benson had indicated that Bulimus bengalensis had a widespread, but patchy, distribution (Correspondence vol. 5, memorandum from W. H. Benson, 5 December 1855). In Origin, pp. 365–76, CD discussed the occurrence of the same species, particularly of plants, on the summits of distant mountain ranges, and argued that this was due not to creation in more than one location, but to the stranding of these species, which once occupied continuous but lower terrains, on mountains, when the temparature rose after the glacial period. He did not mention land-shells in this discussion, but in Natural selection, the longer manuscript of which Origin was an abstract, CD commented (p. 555): land-shells have either been so frequently created, or as I should infer so easily modified, that there do not appear to be many species in common even on mountain-summits as near to each other as the Alps & Pyrenees, or, as I am informed by Mr. Benson, on the Nilghiri & heights of Ceylon.
6
Pulmoniferous: ‘bearing or having lungs (or lung-like organs); pulmonate; … belonging to the group Pulmonifera (=Pulmonata) of gastropod molluscs’ (OED).
7
CD discusses the distribution of freshwater shells in Origin, pp. 385–6.
8
No reply from Benson has been found.
9
James Manby Gully was the proprietor of a hydropathic establishment in Malvern, Worcestershire, at which CD was treated in 1849. In 1851 he took his eldest daughter, Anne Elizabeth Darwin, there for treatment of an illness that proved fatal. See Correspondence vols. 4 and 5.

Please cite as “DCP-LETT-4354,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-4354