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Darwin Correspondence Project

To E. S. Morse   16 September 1873

Down, | Beckenham, Kent.

Septr 16th / 73

Dear Sir

I must have the pleasure of thanking you for your kindness in sending me your essay on the Brachiopoda.1 I have just read it with the greatest interest, & you seem to me (though I am not a competent judge) to make out with remarkable clearness an extremely strong case. What a wonderful change it is to an old naturalist to have to look at these “shells” as “worms”. But as you truly say, as far as external appearance is concerned, the case is not more wonderful than that of cirripedes.2 I have, also, been particularly interested by your remarks on the geological record, & on the lower & older forms in each great class not having been probably protected by calcareous valves or a shell.—3

With the most sincere respect for your admirable labours, I remain | Dear Sir | Yours faithfully | Ch. Darwin

Your woodcut of Lingula is most skillfully introduced to compel one to see its likeness to an annelid.—4


Morse’s essay (Morse 1873) dealt with the systematic position of the Brachiopoda. CD’s annotated copy is in the Darwin Pamphlet Collection–CUL.
Brachiopods were usually classified as molluscs on the basis of their shells. Morse, however, argued that members of the Brachiopoda had not always possessed shells and that they shared morphological characteristics with various groups of worms; he therefore placed the group within Vermes (a now obsolete Linnaean taxon for all non-arthropod invertebrates). Brachiopoda is now regarded as a separate phylum, but its taxonomy is still unstable (see A. Williams et al. 1997–2007, 1: 4–5, 6: xxxiii, xxxix–xlv).
Morse disagreed with those who used evidence of complex structures in older groups of brachiopods to oppose evolution. He suggested that these older groups had probably evolved from even more ancient types that were soft-bodied, and therefore did not leave fossil remains. See Morse 1873, p. 367. CD underlined and scored this statement in his copy of Morse 1873.
Morse had included transverse sections of Lingula and an annelid in Morse 1873, p. 324 (fig. 7) and p. 319 (fig. 1). Lingulid brachiopods were thought hardly to have changed since the Cambrian period and were regarded as ‘living fossils’ (Origin, pp. 306, 486); they have bodies covered by a shell and a worm-like peduncle (Morse 1873, pp. 323–4). Annelida is now a separate phylum of segmented worms.


Morse, Edward Sylvester. 1873. On the systematic position of the Brachiopoda. Proceedings of the Boston Society of Natural History 15: 315–72.

Origin: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. By Charles Darwin. London: John Murray. 1859.


Thanks for ESM’s paper ["On the systematic position of the Brachiopoda", Proc. Boston Soc. Nat. Hist. 15 (1873): 315–72]. "What a wonderful change … to look at these ""shells"" as ""worms""."

Letter details

Letter no.
Charles Robert Darwin
Edward Sylvester Morse
Sent from
Source of text
Joseph R. Sakmyster, ADS Autographs (dealer) (no date)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9058,” accessed on 9 July 2020,

Also published in The Correspondence of Charles Darwin, vol. 21