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Darwin Correspondence Project

To J. D. Dana   5 April [1857]1

Down Bromley Kent

April 5th

My dear Sir

You were so kind as to say that I might trouble you occasionally for information. There is now a point on which I am very curious, & which I think I could make out from your Memoir,2 but, as I once said before, it is incomparably safer not to infer but to quote direct opinion of author.— Sir J. Richardson says the Fish of the cooler temperate parts of the S. Hemisphere present a much stronger analogy to the fish of the same latitudes in the North, than do the strictly Arctic forms to the Antarctic.3

Now I shd. very much like to know how this is with Crustaceans.—4 I have quoted your remarks on the relation of the N. Zealand Crust. to those at these Antipodes;5 but can you tell me how it is with those further south. I fear that there are hardly materials.— Cape Horn may throw some light, but it is hardly far enough south: I think, as far as I can remember, very few Crust. are known from the S. Shetland or icy regions.— But if you will give me a sentence on Crustacea, in relation to Sir J. Richardson’s remark, I shd be particularly obliged.—6

When I shall publish my Book, Heaven only knows, for it daily grows on me; but I do some work every day; but my day’s work, from ill-health is ridiculously short.— I am sorry that I have no scientific news to communicate, for I have left home very seldom of late owing to my health having been worse than usual. The most interesting discovery, I think, made for some years, has been the astonishing find of Mammalian remains in the Purbeck beds;7 I have seen at Dr. Falconer’s many of the specimens—8 They give one an astonishing idea of the richness of the Fauna at that period. Lyell, as you may suppose is delighted. I never saw anything more curious than the manner in which the Plagyoulax (or some such name) connects the living Hypsiprimnus & the Triassic mammifers, about which the doubts formerly held must now be given up; for it must assuredly have been a Mammifer.—9

Some small & very highly organised Lizards in same bed are, I think, even more interesting than the Mammalian remains.— This discovery has made a deep impression on some of our geologists, as Prestwich, who have been strongly inclined to trust in negative evidence. Lyell will very soon publish a little supplement to his Elements & will give an outline of these new facts & many others which he picked up on the continent last autumn.—10 He visited with Barrande his celebrated region; & will discuss B.’s colonies, which always troubled me as great anomaly.—11

Owen has lately published a new Classification of mammals, taken from structures of Brain;12 so great an authority ought to be right, but I cannot help always having doubts on a classification founded on one character, however important.— I have had of late a good deal of correspondence with Asa Gray, who has been infinitely kind in giving me valuable information.— I sometimes hope that my Book will be useful as comparing the results which different authors from different data have arrived at; however erroneous my general conclusions may prove.—

Whenever you have time to write, tell me a little what you are about, & believe me, My dear Sir | Your’s very sincerely | Ch. Darwin


The year is provided by the references to the recent publication of Owen 1857b and to the forthcoming publication of C. Lyell 1857a.
Dana 1853. Dana had published the section from Dana 1852[–3] on the classification and geographical distribution of Crustacea separately in 1853. CD’s presentation copy is in the Darwin Library–CUL.
In Natural selection, p. 555, CD cited J. Richardson 1845, p. 189, on this point. See also letter from John Richardson, 17 July 1856.
CD was gathering cases from the zoological realm to test his hypothesis of the migration of plants and animals ‘from north to south during the glacial epoch’ (Natural selection, p. 554). He was seeking examples of northern temperate species, or closely allied species, that were also found in the southern hemisphere.
‘Well does Prof. Dana remark that “it is certainly a wonderful fact that New Zealand should have a closer resemblance in its Crustacea to Great Britain, its antipode, than to any other part of the world,” ’ (Natural selection, p. 557). CD refers to Dana 1853, p. 1587.
Charles Lyell had asked Hugh Falconer to examine the fossils from the Purbeck beds (Wilson ed. 1970, p. lii). Falconer published a description of two species of a new mammalian genus Plagiaulax later in the year (Falconer 1857).
According to Falconer, the Plagiaulax was decidedly ‘a marsupial form of rodent, constituting a peculiar type of the family to which Hypsiprymnus [the kangaroo-rat of Australia] belongs’ (Falconer 1857, p. 274). Descriptions were also incorporated into a supplement to Lyell’s Elements of geology (see n. 10, below).
C. Lyell 1857a. Copies of this and the revised edition, C. Lyell 1857b, are in the Darwin Library–CUL. Both contain annotations.
Joseph Barrande, a French geologist living in exile in Prague, had found a ‘colony’ of Upper Silurian fossils in the Lower Silurian strata, which Lyell, in a letter of 23 August 1856 to Leonard Horner, called ‘the most singular and, at first sight at least, anomalous fact I ever remember to have verified in paleontological geology.’ (K. M. Lyell ed. 1881, 2: 223). In his supplement to the Manual of elementary geology (C. Lyell 1857a), Lyell reported Barrande’s conclusion that each period of geological time was characterised by a fully diversified flora and fauna, rather than a uniform assemblage spread out over the globe. To Barrande, the ‘colony’ was merely a pocket of animals that then increased greatly in numbers during the following geological epoch, so giving the appearance of an anomaly in the Lower Silurian. See C. Lyell 1857a, p. 31–4.
Owen 1857b.


Natural selection: Charles Darwin’s Natural selection: being the second part of his big species book written from 1856 to 1858. Edited by R. C. Stauffer. Cambridge: Cambridge University Press. 1975.

Richardson, John. 1845. Report on the ichthyology of the seas of China and Japan. Report of the 15th meeting of the British Association for the Advancement of Science held at Cambridge, pp. 187–320.


Asks whether Crustacea from temperate parts of the Southern Hemisphere are more strongly analogous to those in same latitudes of the Northern Hemisphere than are Arctic to Antarctic Crustacea.

Discusses astonishing finds of mammalian and reptilian remains in Purbeck beds; notes reactions of Lyell.

Has doubts about Richard Owen’s recent classification of mammals [J. Proc. Linn. Soc. Lond. (Zool.) 2 (1858): 1–37].

Works away [on Natural selection].

Asa Gray has given valuable assistance.

Letter details

Letter no.
Charles Robert Darwin
James Dwight Dana
Sent from
Source of text
Yale University Library: Manuscripts and Archives (Dana Family Papers (MS 164) Series 1, Box 2, folder 44)
Physical description
ALS 6pp

Please cite as

Darwin Correspondence Project, “Letter no. 2072,” accessed on 24 May 2024,

Also published in The Correspondence of Charles Darwin, vol. 6