From A. R. Wallace   [14 September 1868]1

9, St. Marks’ Crescent | N.W.

Monday Evening

Dear Darwin

I send you by post a pair of the Euchirus longimanus   They are not quite perfect and are very rotten from being kept so long in open boxes but will perhaps answer your purpose.2

I send on the other side two or three notes on sexual differences which I find in an old note book, but I fear there is nothing of interest.

I have to thank you for a most agreeable visit, & my wife was so pleased3   I rather think she was sorry to be obliged to come home again.

With kind regards to Mrs. Darwin & all your family

I remain | Yours very sincerely | Alfred R. Wallace—

Euchirus longimanus.. (Amboyna, Ceram) when in motion makes a low hissing sound caused by protrusion and contraction of the abdomen. When sezed it also produces a grating sound by rubbing the hind tibiæ against the edges of the elytra.4

Callichroma dorycus. Boisd. (N. Guinea)5 I have a note that the ♂. of this musk beetle has a fine odour of ottar of roses; the ♀ having only a slight disagreeable smell.

Mutilla sp.6 (Celebes)

Winged males seize females by head or thorax, fly with them, settle & shake them violently till they submit to cop.

I have a note that the female in the genus Glenea (Longicorns)7 feigns death, the male not;—but I shd. hardly like to be sure of this.

CD annotations

1.1 They are … family 4.1] crossed pencil
7.1 Callichroma … smell. 7.2] crossed pencil
10.1 I have … of this. 10.2] crossed pencil
Top of letter: ‘Euchirus’ pencil
1
The date is established by the reference to the weekend visit that Wallace and his wife, Annie, made to Down House (see n. 3, below).
2
CD and Wallace may have discussed the long-armed chafer beetle, Euchirus longimanus, during Wallace’s visit to Down from 12 to 13 September. Wallace collected the specimens in the Moluccas in the 1850s (A. R. Wallace 1869, pp. 309, 406).
3
The Wallaces visited Down House on Saturday 12 and Sunday 13 September 1868 (see letter from A. R. Wallace, 5 September [1868] and n. 2).
4
For CD’s discussion of the sounds made by Euchirus longimanus, including Wallace’s account, see Descent 1: 381–2. Wallace’s specimens (see n. 2, above) were from two islands of the Moluccas, Ceram and Amboyna (now Ambon or Amboina).
5
A Cerambyx dorycus was described by Boisduval in 1835 (see Index animalium). The species, a longhorn beetle, is now Chloridolum dorycum (E. Richard Hoebeke, personal communication). All members of the tribe to which this beetle belongs, the Callichromini (or to some authorities, Callichromatini), produce strong odours (see Linsley 1959, p. 116). Wallace described his beetle-collecting in New Guinea in A. R. Wallace 1869, pp. 512–13.
6
Mutilla, a genus in the Hymenoptera, is a wasp.
7
Glenea, in the family Cerambycidae, is a longicorn genus comprising approximately 600 species from Africa, Asia, and the south Pacific.

Please cite as “DCP-LETT-6364,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-6364