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Darwin Correspondence Project

To H. W. Bates   19 February [1868]1

Down. | Bromley. | Kent. S.E.

Feb. 19th

My dear Bates

I am in utter confusion; will you kindly clarify my mind.— Westwood divides saltatorial Orthopt. (modern. Class. vol. 2. p. 439)2 into

Achetidæ = ?
Gryllidæ = ?
Locustidæ = ?

Now you speak (amazons vol. I. p. 250) of Achetidæ, Locustidæ & Acridiidæ.— Now will you homologise these families for me, & tell which terms will be most generally understood, which I care more about than which are most strictly correct.3

Again, & more important for me, you say that (p. 252) in the Achetidæ (I suppose of Westwood likewise) “the wing-cases are symmetrical both have straight edges … a distinct portion is not set apart … for sound-producing” … 4

Now how can I reconcile this with Westwood (p. 440) who gives drawing of the two wings which are not strictly symmetrical, one is ♂ & the other ♀ & one of which is furnished “with a distinct portion” for sound producing.—5 Is it that some species of crickets have both wings similar?

I shd. be grateful if you would kindly aid me as far as you can, & excuse me troubling you

Yours very sincerely | C. Darwin

Harris places Platyphyllum concavum, the “Katy-did”, in the Gryllidæ, is this the Gryllidæ of Westwood?6

I suppose the “Field cricket” belongs to Achetidæ of all authors.—7

Your Chlorocœtus cannot belong to the Locustidæ of Westwood, but I suppose to his Gryllidæ.8


The year is established by the relationship between this letter and the letter from H. W. Bates, 21 February 1868.
Saltatoria was a term commonly used for the jumping Orthoptera, such as grasshoppers, locusts, and crickets (see, for example, T. W. Harris 1842, p. 116). The taxonomy of Saltatoria is given in Westwood 1839–40, 1: 439.
Bates described the Locustidae as a group intermediate between the Achetidae (crickets) and the Acridiidae (grasshoppers) (Bates 1863, 1: 250–1). In his copy of Bates 1863, CD underlined these family names and wrote in the margin ‘partly Gryllidae of Westwood’ (see Marginalia 1: 35–7). For a modern taxonomy of the Orthoptera, see Harz 1969–74. Crickets are now the family Gryllidae. The family Locustidae is now subsumed within the Acrididae (short-horned grasshoppers).
This passage in Bates 1863, 1: 252–3, is scored in CD’s copy (Marginalia 1: 36).
CD is apparently paraphrasing the description of the wing-covers of Acheta domestica in Westwood 1839–40, 1: 440–2. Acheta domestica is now A. domesticus, the house cricket.
Thaddeus William Harris placed Platyphyllum concavum in the family Gryllidae (T. W. Harris 1842, pp. 127–8; on the Gryllidae, see also Westwood 1839–40, 1: 450–56). CD’s annotated copy of Harris 1842 is in the Darwin Library–CUL. CD cited Harris’s description of the katydid in Descent 1: 352–3 and 357, but placed the insect in the family Locustidae. Katydids are now in the family Tettigoniidae. Platyphyllum concavum is now Pterophylla camellifolia, the common true katydid.
The field cricket, Acheta campestris, is described in Westwood 1839–40, 1: 444–5, where it is placed in the family Achetidae. Acheta campestris is now Gryllus campestris (family Gryllidae). CD discussed G. campestris in Descent 1: 353–4.
Bates placed the ‘musical cricket’ (Chlorocoelus tananá) in the family Locustidae (Bates 1863, 1: 250–2). CD used the figure of C. tanana from Bates 1863 in Descent 1: 355. C. tanana is now Thliboscelus hypericifolius (family Tettigoniidae, katydids and long-horned grasshoppers).


Bates, Henry Walter. 1863. The naturalist on the River Amazons. A record of adventures, habits of animals, sketches of Brazilian and Indian life, and aspects of nature under the equator, during eleven years of travel. 2 vols. London: John Murray.

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

Harris, Thaddeus William. 1842. A treatise on some of the insects of New England, which are injurious to vegetation. Cambridge, Mass.: John Owen.

Marginalia: Charles Darwin’s marginalia. Edited by Mario A. Di Gregorio with the assistance of Nicholas W. Gill. Vol. 1. New York and London: Garland Publishing. 1990.

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.


CD in utter confusion about differences between J. O. Westwood and HWB on division of certain insects. Asks if HWB will homologise certain families for him, telling him which terms would be most generally understood.

Asks also about differences on sound-producing organs of Achetidae Gryllidae.

Letter details

Letter no.
Charles Robert Darwin
Henry Walter Bates
Sent from
Source of text
Cleveland Health Sciences Library (Robert M. Stecher collection)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5895,” accessed on 18 January 2022,

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