To Anton Dohrn 26 November 
Down. | Bromley. | Kent. S.E.
I thank you sincerely for having sent me your paper on the morphology of the Arthropoda, which I was very curious to read.1 It is a most deeply interesting subject, & if you finally succeed in showing how far the head-organs are homologous in the various classes, you will indeed have achieved a triumph in science.—2 Allow me to thank you cordially for the generous & much too honourable manner in which you refer to my work.—3
If you could get fresh specimens of Scalpellum (Cirripedia), you would probably succeed in finding just-hatched larvæ in the sack; & these larvæ are so large that they are excellent for observation.4
I cannot yet quite persuade myself that the view which I have taken in my vol. on Balanidæ p. 105, of the homologies of the appendages is wrong. I still believe (though Fritz Müller writes to me that he thinks I am mistaken) that I saw in the anterior-lateral horns of the Carapace, the prehensile antennæ in process of development.5 I sincerely wish you success in your studies, than which nothing can be more interesting.
I received some time ago a valuable memoir from you on certain ancient fossil insects, for which I am much obliged.6
When you next see Prof. E. Häckel, pray give him my kindest remembrances.7
With the most sincere respect, I remain | Dear Sir | Yours very faithfully | Ch. Darwin
Thanks AD for his paper on "Morphology of the Arthropoda" [Rep. BAAS 37 (1867) pt 2: 82], a deeply interesting subject.
Suggests he examine specimens of Scalpellum.
Fritz Müller thinks CD is mistaken, but CD cannot persuade himself he was wrong in his observations on Balanidae [Living Cirripedia 2: 105].
Please cite as
Darwin Correspondence Project, “Letter no. 5698,” accessed on 11 February 2016, http://www.darwinproject.ac.uk/DCP-LETT-5698