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Darwin Correspondence Project

From Charles Owen Waterhouse   12 February 1868

British Museum,

Feb. 12th. 1868.

Dear Sir,

I received your letter of yesterday in the evening & it will give me much pleasure to search out the information you require—1

It will, however, take a short time to look out those that I do not already know—

Mr. Murray in his paper on blind insects (which I suppose you know) mentions the following blind beetles2

Geodephaga 3
Anillus, 1 species
Anophthalmus, 6 species.4
Glyptomerus 1 species6
Necrophaga 7
X Aglenus, 1. species.
X Anommatus, 1, spe.
Clinidium, 2, spes.
Langelandia, 1, spe.
Amaurops 1, spe.
Leptomastax 1 spe.
X Leptinus 1 spe.
X Adelops, 9 spes
Leptodirus, 3 spes.8
Rhynchophora 9
Troglorhynchus, 1 species.10
Pseudotrimera 11
X Claviger, 3 spes.
Adranes, 1 spe.
X Ptilium (some blind, 3. some with eyes)12

All of these that I know (marked with x) are more or less testaceous, & I expect the others are so also— Some of them are very pubescent which gives them a dull appearance, but most of them are bright & shining—13

If possible I will tomorrow look at all these insects & give you the result as soon as I can.

With regard to the Brentus14 (which Mr. Smith15 pointed out to me this morning) I can only tell you at present that the left mandible is always the one produced—

I believe that this development of the jaw is simply to act as a centre-bit (as most of the strange forms of horns &c on the heads & thoraces of coleoptera)—16 As the ♂ always comes out first there is no occasion for the ♀ to be armed as she may make her escape by the channels cut by the ♂.

I think that there are many coleopterous insects in which one mandible is larger than the other—as in the genus Aagathidium, one of the species has a horn on the enlarged mandible.

It will be interesting to me now to find out whether it is always the left mandible that is enlarged—17

I shall always be happy to answer any questions that may lie in my power (provided my time permit) so please ask—

I remain, | Yours sincerely, | Chas. O. Waterhouse

Chas. Darwin Esqre.

CD annotations

4.3 Anophthalmus] marked with cross pencil
4.5 Glyptomerus] marked with cross pencil
4.10 Langelandia] marked with cross pencil
4.12 Leptomastax] marked with cross pencil
Top of letter: ‘Size of male Brentus. | Use of Horn in Lamellicorns’18 pencil


CD’s letter to Waterhouse has not been found.
Waterhouse refers to Andrew Murray’s paper, ‘On insect-vision and blind insects’ (A. Murray 1857).
Geodephaga was a group of predaceous land beetles. Most of the higher taxa listed in this letter were introduced by Pierre André Latreille (Latreille [1802–5]). On their definition and application in nineteenth-century entomology, see Westwood 1839–40; for the Geodephaga, see ibid. 1: 47.
Anillus and Anophthalmus are genera in the family Carabidae.
Brachelytra were a group of beetles corresponding roughly to the modern family Staphylinidae, rove beetles (see Westwood 1839–40, 1: 161–2).
Glyptomerus is in the family Staphylinidae.
Necrophaga was a group of carrion-feeding beetles (see Westwood 1839–40, 1: 132).
The modern taxonomy for these genera is: Aglenus, family Salpingidae, Anommatus, family Bothrideridae, Clinidium, family Carabidae, Langelandia, family Zopheridae, Amaurops, family Staphylinidae, Leptomastax, family Scydmaenidae, Leptinus, family Leiodidae, Adelops, now Ptomaphagus, family Leiodidae, Leptodirus, family Leiodidae.
Rhynchophora was a group of beetles roughly equivalent to the modern family Curculionidae, weevils and snout beetles (see Westwood 1839–40, 1: 326).
Troglorhynchus is now a subgenus of the genus Otiorhynchus in the family Curculionidae.
Pseudotrimera was a group proposed by John Obadiah Westwood, comprising Coleoptera with four-jointed tarsi (Westwood 1839–40, 1: 44, 390).
Claviger and Adranes are now in the family Staphylinidae; Ptilium is in the family Ptiliidae (featherwing beetles).
CD cited Waterhouse on the point that blind beetles never exhibit bright colours, though they have polished coats, in Descent 1: 367.
Brentus is a genus of straight-snouted weevils (family Brentidae, straight-snouted weevils and pear-shaped weevils).
Frederick Smith had corresponded with CD on bees and other insects (Correspondence vols. 6–10, 12), and is cited in Descent.
CD concluded that horns and certain other projections in Coleoptera had been acquired as ornaments through sexual selection in Descent 1: 371–5.
CD discussed the variable size and structure of mandibles in Coleoptera in Descent 1: 344, 376–7, and of chelae in crustacea in ibid., pp. 330–2; he noted that it was often the right claw that was enlarged in male crustacea.
CD’s annotations were evidently for his reply to Waterhouse, which has not been found; see, however, the letter from C. O. Waterhouse, 19 February 1868.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

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

Latreille, Pierre André. [1802–5.] Histoire naturelle, générale et particuliere, des crustacés et des insectes. (Suites à Buffon.) 14 vols. Paris: F. Dufart.

Murray, Andrew. 1857. On insect-vision and blind insects. Edinburgh New Philosophical Journal n.s. 6: 120–38.

Westwood, John Obadiah. 1839–40. An introduction to the modern classification of insects; founded on the natural habits and corresponding organisation of the different families. 2 vols. London: Longman, Orme, Brown, Green, and Longman.


On blind beetles [see Descent 1: 367].

Development of mandibles in Brentus.

Letter details

Letter no.
Charles Owen Waterhouse
Charles Robert Darwin
Sent from
British Museum
Source of text
DAR 82: A74–5
Physical description
ALS 4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 5870,” accessed on 19 July 2024,

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