u- 



Allen on Sexual Selection and the Nesting of Birch. [April 



enemies." Again, it serves to conceal the eggs, where they are. 

 as in many cases, conspicuous ; and also allows the gaudily plu- 

 maged male bird to assist in incubation ; yet this also happens 

 when the nest is an open one. "If we grant," says Mr. Dixon, 

 ••that these domed nests are built for other purposes than con- 

 cealment of the sitting female, it is easy to explain the great 

 difference of colour between the sexes. The more brilliant 

 colours of the males have been obtained by sexual selection" ; 

 and proceeds to cite cases where the domed nest is evidently not 

 built for the purpose of concealing the female. This dictum, 

 however, appears to be the only 'proof educed from the consid- 

 eration of this group, which furnishes such "convincing proofs 

 of the truths of the theory of natural selection." The author 

 then considers 'Birds' Nests' and -Birds' Eggs, studied in relation 

 to their colour.' The last subject is treated at some length in a 

 thoroughly rational and admirable manner, but respecting 'Birds' 

 Nests' we beg to offer one or two criticisms. But first let us 

 return to the first part of the subject, the coloration of female 

 birds in respect to the manner of nesting. 



In my former paper on this subject I ventured to say. "The 

 most surprising thing about Mr. Wallace's -Theory of Bird's Nests' 

 is its inadequacy,. and its irrelevancy to the fac's it was proposed 

 to explain" ; and further attention to the subject only serves to 

 confirm my conviction that the above statement was not incon- 

 siderately made. Mr. Wallace says that the -Hist thing we are 

 taught' by a consideration of the facts involved, is -'that there is 

 no incapacity in the female sex among birds to receive the same 

 bright hues and strongly contrasted tints with which their part- 

 ners are so often decorated, since whenever they are protected 

 and concealed during the period of incubation they are similarly 

 adorned."* In point of fact, however, this statement is far from 

 correct, for it often happens that where the males are especially 

 brilliantly colored and the females are exceptionally dull-colored. 

 they either build domed nests or nest in places of concealment. 

 as in the Superb Warblers (genus Malurus) of Australia, and the 

 great family of Sunbirds (Nectariniida?) . etc. ;t while on the 



* The italics are Mr. Wallace's own. 

 t Numerous individual cases may be cited among many other families, where the 

 rule is an open nest, and the exceptions of concealed or domed nests are presented by 

 species in which the sexual contrast in the color of the birds is greaterthan among their 

 near allies which build an open nest. 



