To Osbert Salvin 10 September 
Down, | Beckenham, Kent.
My dear Mr. Salvin
I am going to beg a favour of you,—that is if you can grant it easily.— I believe that you have studied the Duck-family, & I want to know something about the gradation of character in the lamellæ of their beaks, just to illustrate another point.1 In the Shoveller I find that the lamellæ are very prominent & fine, & in the Australian Malacorhynchus even finer; but I have not as yet carefully cleaned & compared the beaks of my specimens.—2 In the common Duck they are far less developed & prominent;3 & in the common Goose even less so, & seem to serve more as teeth, rather than as a sifting apparatus.—4 Now can you tell me whether the lamellæ are less developed in any true Duck than in the common Duck? As it would be fairer to end the series with a Duck rather than with a Goose.— I shd., however, much like to know whether the lamellæ are less developed or prominent in any other species of goose than in the common kind.—
Are the lamellæ more prominent & finer in any Duck than in the Shoveller & Malacorhynchus? Pray do not for one moment suppose that I am so unreasonable as to ask you to compare many species for me; but I have thought that your memory might guide you to one or two species, & then a glance would answer my query.
Pray forgive me for troubling you & believe me | Yours very sincerely | Ch. Darwin
CD is interested in the gradation of character in the lamellae of the beaks of ducks. He finds that they are less developed or prominent in the common duck and goose than in true ducks. Is OS able to provide him with any information on this subject?
Please cite as
Darwin Correspondence Project, “Letter no. 7932A,” accessed on 31 August 2016, http://www.darwinproject.ac.uk/DCP-LETT-7932A