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Darwin Correspondence Project

From C. S. Bate   24 May 1868

8, Mulgrave Place, | Plymouth.

My dear Sir

In a collection of Crustacea recently added to the British Museum—I saw a day or two since four specimens of Gelasimus from Zanzibar, all of which had the left arm the larger. When I wrote to you previously I felt a doubt on the subject1

As far as my experience goes all long & large armed crustacea are indolent & sub-burrowing creatures. May not the big claw be for the purpose of reaching far & drawing food within reach of the smaller & more directly feeding claws and to seize the female when at a distance?—2

Yours sincerely | C. Spence Bate

May 24—68

CD annotations

1.1 In … distance?— 2.4] crossed pencil
Top of letter: ‘left chelæ [interl] are largerblue crayon; ‘Used’ pencil


See letter from C. S. Bate, [17 February 1868]. In Descent 1: 330, CD wrote that Bate had informed him that the right-hand chela (pincer) was generally, though not invariably, the larger. Gelasimus (now Uca) is a genus of fiddler crabs.
In Descent 1: 331, CD suggested that the main use of enormously developed pincers in the male was to seize and hold the female.


Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.


On structure of Crustacea; size of claws [see Descent 1: 330–1].

Letter details

Letter no.
Charles Spence Bate
Charles Robert Darwin
Sent from
Source of text
DAR 82: A69–70
Physical description
2pp †

Please cite as

Darwin Correspondence Project, “Letter no. 6204,” accessed on 26 October 2021,

Also published in The Correspondence of Charles Darwin, vol. 16