To John Lubbock 3 August 1869
Aug 3d. 1869
My dear Lubbock
I am at home again & thank Heavens at work again;1 & I want very much to plague you with 2 or 3 questions.
I write to mention, (& perhaps give woodcut) as curious sexual difference, the right-hand antenna in ♂ Labidocera, Darwinii as described by you in Annal & Mag Vol. XI. (1853) Pl. I. Now will you tell me in a few words the character of the left-hand antenna, which resembles both antennæ in ♀.— May I say that these antennæ consist of “simple tapering joints less in number than in the right-hand antenna?”2 Or are the joints equally numerous, though different in form?
In the Crustacean which has the right-antenna modified, is one of the hinder thoracic legs generally or only sometimes converted into a forceps? & is this forceps on the same right side of the body with the modified right antenna?
Lastly, I can find no account of any secondary sexual differences in the Myriapoda, except that it is said (I know not do you know? whether on good authority) that in Lithobius the female has a pair of pincers or forceps at entrance of vulva.—3 Do you know whether the males ever differ from ♀s in size, colour, jaws for fighting, or prehensile organs?
I have looked at the sentence in the Origin about which you wrote, but I find that I do not so expressly imply that Agassiz believes in descent or derivation of species: I have, however, by mere good luck altered the sentence in the new Edit. of Origin.—4
Have you settled anything about Mr Powell.5
Pray forgive me for troubling you & believe me | My dear Lubbock | Yours most truly | Ch. Darwin
P.S. One other question: in such Entomostraca as you know are the males larger than the females, as is the case with the stalk-eyed & sessile-eyed crustaceans?6
Sexual differences in Labidocera darwinii, in Entomostraca, and Myriapoda.
Please cite as
Darwin Correspondence Project, “Letter no. 6851,” accessed on 22 October 2016, http://www.darwinproject.ac.uk/DCP-LETT-6851