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
Footnotes
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