JiiAP. XVI, Birds — Young like Adult Males. 479 



plnmes with more strongly contrasted colours ; nevertheloss he 

 undertakes the whole duty of incubation." 



1 will specify the few other cases known to me, in which the 

 feraale is more conspicuously coloured than the male, although 

 nothing is known about the manner of incubation. With the 

 carrion-hawk of the Falkland Islands {Milvago leucurus).! was 

 much surprised to find by dissection that the individuals, which 

 bad all their tints strongly pronounced, with the cere and legs 

 orange-coloured, were the adult females; whilst those with 

 iluller plumage and grey legs were the males or the young. In 

 an Australian tree-creeper {Olimacteris trythrops) the female 

 differs from the male in " being adorned with beautiful, ra^ 

 " diated, rufous markings on the throat, the male having this 

 " part quite plain." Lastly, in an Australian night-jar "the 

 " female always exceeds the male in size and in the brilliance 

 "of her tints ; the males, on the other hand, have two white 

 " spots on the primaries more conspicuous than in the female."''^'' 



We thus see that the cases in which female birds are more 

 conspicuously coloured than the males, with the young in their 

 immature plumage resembling the adult males instead of tho 

 adult females, as in the previous class, are not numerous, though 

 they are distributed in various Orders. The amount of differ- 

 ence, also, between the sexes is incomparably less than that 

 which frequently occurs in the last class ; so' that the cause ot 

 the difference, whatever it may have been has here acted on the 

 females either less energetically or less persistently than on the 



''* Mr. Sclater, on the incubation than that of the male ; the head of 



of the Struthiones, ' Proc. Zool. Soe.,' the male is of a rich dark bronzed 



June 9, 1863. So it is with the colour, and his back is clothed with 



Rhea darwinii : Captain Musters says finely pencilled slate-coloured fea- 



(' At home with the Patagonians,' thers, so that altogether he may be 



1871, p. .128), that the male is considered as the more beautiful of 



larger, stronger and swifter than the two. He is larger and more 



the female, and of slightly darker pugnacious than the female, and 



colours ; yet he takes sole charge of does not sit on the eggs. So that 



the eggs and of the young, just as in all these respects this species 



does the male of the common species comes under our first class of cases ; 



uf Rhea. . but Mr. Sclater (' Proo. Zool. Hoc' 



^' For the Milvago, see 'Zoology 1866, p. 150) was much surprised 



of the Voyage of the Beagle, ' to observe that the young of both 



Birds, 1841, p. 16. For the Climac- sexes, when about three months old, 



teris. and night-jar (Eurostopodus), resembled in their dark heads and 



eee Gould's ' Handbook to the Birds necks the adult males, instead of 



:f Australia,' vol. i. pp. 602 and 97. the adult females ; so that it would 



The New Zealand shieldrake ( Ta- appear in this case that the females 



doma variegatd) offers a quite ano- have been modified, whilst the malca 



malous case ; the head of the female and the young have retained a 



a pure white, and her back is redder former state of plumage. 



