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Darwin Correspondence Project

From Robert McLachlan   20 February 1871

39, Limes Grove, | Lewisham, S.E.

20 Feby. 1871.

My dear Sir

I have to thank you heartily for your very handsome present the “Descent of Man”.1 When I have studied the vols. I will forward to you any additional information bearing upon the subject, as treated by you, that may occur to me.2

I content myself now with one remark. You have put considerable stress upon the inequality in the chelae, jaws &c of certain Crustacea & Beetles.3 Now a curious instance occurs in a small Caddis-fly—Setodes interrupta F.—in which the anal appendices of the ♂ present great inequality— I have examined many specimens, & in all I find that the left hand app. intermed. is nearly twice the length of the right (See. Trans. Ent. Soc. 3rd series, vol. 5, p. 122).4 Probably the appendices of 2000 species of Neuroptera have been examined by me, & in no other case have I observed a like inequality.

Your’s very faithfully | R. Mc. Lachlan

CD annotations

1.1 I have … to me. 1.3] crossed pencil
2.2 Crustacea & Beetles] underl pencil
Top of letter: ‘not worth using or as foot-note’ pencil

Footnotes

McLachlan’s name appears on CD’s presentation list for Descent (Appendix IV).
No further letter from McLachlan about Descent has been found.
See Descent 1: 330–2, 344.
McLachlan refers to McLachlan 1865b. Setodes interrupta is now Leptocerus interruptus.

Bibliography

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

Summary

Thanks for Descent; will forward any information he has after he has studied it.

Instance of inequality in left and right anal appendices of caddis-fly.

Letter details

Letter no.
DCP-LETT-7498
From
Robert McLachlan
To
Charles Robert Darwin
Sent from
Lewisham
Source of text
DAR 89: 79–80
Physical description
ALS 2pp inc †

Please cite as

Darwin Correspondence Project, “Letter no. 7498,” accessed on 29 March 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-7498.xml

Also published in The Correspondence of Charles Darwin, vol. 19

letter