CHARLES DARWIN 295 



P.S. As I am writing, I will ask one other ques- 

 tion, for the chance of your being able to answer it. 

 Does the male black Australian swan, or the black and 

 white S. American swan, differ from the females in 

 plumage ? i.e. in the intensity of the black, or in the 

 amount of black in the black-necked species ? 



Down, Bromley, Kent, S.E., 



March 4, 1867. 



MY DEAR SIR, 



Very many thanks about the Dotterel, and I 

 am pleased to hear of this additional evidence. I have 

 looked to Swinhoe's papers, but the case does not seem 

 very conclusive. After writing to you I remembered 

 that the female of the Carrion-hawk of the Falkland Fs. 

 (formerly called Polyborus N. Zealandii) is very much 

 brighter coloured than the male, as I ascertained 

 (" Zool. Voyage of Beagle: Birds") by dissection; I 

 have written to the Missionaries there about its 

 nidification and if I receive any answer, will in- 

 form you. 



The other day I thought I had got a case at the 

 Zoological Gardens in the Casuannus galeatus, in 

 which the female has the finest and brightest caruncles, 

 etc., but Sclater tells me it would be rash to trust to 

 the comparison of a single pair, and he tells me that 

 the male Ostrich has the finest plumes. 

 With my best thanks, 



I remain my dear Sir, 

 Yours very sincerely, 



CHARLES DARWIN. 



P.S. Mr. Blyth tells me that according to Jerdan 

 the natives say the male Turnix alone incubates and 

 attends to young. 



There is another consideration which might lead to 

 the female being the most beautiful, viz., if they were 

 the more numerous than the males and the species were 

 not polygamous, for in this case the more beautiful 

 females would be selected. 



