To Albert Günther 12 May 1
Down.| Bromley.| Kent. S.E.
My dear Dr. Günther
You were so kind as to say that I might ask you some questions.— I have roughly written out my short discussion about secondary sexual differences of fishes, chiefly from your information; & some points have occurred to me about which I shd be grateful for answers.—2 I enclose my queries; & I hope & think they will not cause you great trouble, for “yes” or “no” or “do not know” will answer most of them. Will you write at back of my paper & put corresponding numbers to answers?—3
Be so, kind as to give enclosed note to Mr Ford, when next at the Museum, it is about figures of fishes.—4
When I saw you in London, you said that you would run down here. We shall be most happy to see you at anytime, & you can come down on the Saturday evening or Sunday morning, whichever suits you best, & sleep here & in all probability I can send you in some vehicle as early as you like on Monday morning to the Station.— Bromley is 6 miles distant; but Orpington, (a new station on S. E. Railway) is only about 3 miles distant, though more distant from London.—5
I shd like to hear whenever you have time & inclination to come here, for this reason, that I may be idle in the morning, for if I do my full morning’s work, I am generally dead tired in the evening,— my usual state being one of fatigue.—
With most sincere thanks for all the very great kindness which you have shown towards me, pray believe me | Yours very sincerely | C. Darwin
(1) Am I right in supposing that the two sexes of Callionymus are described by Yarrell as C. Lyra (the male) and C. dracunculus as the female? Yarrell says nothing about the first dorsal fin being brightly striped in C. Lyra which, if I am not mistaken, you said was the case.6
(2) Am I right in believing that both sexes of some species of Blennius have a crest, & that neither sex is thus furnished in B. pholis?7
(3) Yarrell speaks in a manner which makes me suppose that perhaps both sexes of some Gasterostei are crimson beneath. Is this the case? I see that neither sex is crimson beneath in some species.8
(4) Are the sexes known to differ in Colour in any other species of Labrus, besides L. mixtus?9
(5) Cuvier says that some species of Gobius make nests;10 now do any of these species differ at all sexually in colour?
(6) Do any of those fishes which deposit their eggs within the mouth or within the marsupial sac of the male differ sexually in colour?
(7) are Crenilabrus massa and melops, which build nests, brightly coloured species; or is it known that they become brighter during the breeding season?11
(8) Do any other genera besides crenilabrus, gobius & gasterosteus build nests.12
(9) M. Carbonnier maintains that the females of all fishes grow to a larger size than the males.13 Is there any truth in this? You told me of some Cyprinodontae in which this is the case. Do you believe that the females of many kinds of fish are larger than the males? Or do you know of any cases in which the males are larger than the females?
Sends some questions on secondary sexual differences of fishes [missing], which he hopes AG will look over.
Invites AG to come to Down.
Encloses queries on sexual differences and nest-building habits of fish.
Please cite as
Darwin Correspondence Project, “Letter no. 7186,” accessed on 30 July 2016, http://www.darwinproject.ac.uk/DCP-LETT-7186