To Albert Günther   25 February 1874

My dear D^r Günther

I have given, in my Descent, vol. 2. p. 12, an account from you of the curious brushes on the sides of the 2 sexes of Monacanthus.¹ Now you no doubt will have seen an acct in the American Naturalist (1871 p. 119) of the brush-like scales with which the males alone of Mallotus villosus are provided, by which apparently 2 males hold the female during the act of spawning.²

Now will you be so kind as to tell me to what families the Monacanthus & Mallotus belong; that is, whether they are allied? Am I right in supposing that the use of the brush-like males is the same in these 2 genera?

I sh^d be very much obliged for any information & remain | yours sincerely | Ch. Darwin

It seems that with many Cyprinidæ two males attend on one female; what an odd anomaly this seems to be.—³