SEXUAL SELECTION 627 



the sexes of which are alike during both the summer and 

 winter, the young may resemble the adults, first, in their 

 winter dress; secondly, and this is of much rarer occurrence, 

 in their summer dress; thirdly, they may be intermediate 

 between these two states; and, fourthly, they may difEer 

 greatly from the adults at all seasons. We have an in- 

 stance of the first of these four cases in one of the egrets 

 of India {JBuphus coromandus), in which the young and the 

 adults of both sexes are white during the winter, the adults 

 becoming golden-buff during the summer. With the gaper 

 {Anastomus oscitans) of India we have a similar case, but 

 the colors are reversed; for the young and the adults of 

 both sexes are gray and black during the winter, the adults 

 becoming white during the summer.*' As an instance of the 

 second case, the young of the razor-bill (Alca tarda, Linn.), 

 in an early state of plumage, are colored like the adults dur- 

 ing the summer; and the voung of the white-crowned spar- 

 row of North America (Fringilla leucophrys), as soon as 

 fledged, have elegant white stripes' on their heads, which 

 are lost by the young and the old during the winter." 

 With respect to the third case, namely, that of the young 

 having an intermediate character between the summer and 

 winter adult plumages, Yarrell," insists that this occurs 

 with many waders. Lastly, in regard to the young differ- 

 ing greatly from both sexes in their adult summer and win- 

 ter plumages, this occurs with some herons and egrets of 

 North America and India — the young alone being white. 

 I will make only a few remarks on these complicated 

 cases. When the young resemble the females in their sum- 

 mer dress, or the adults of both sexes in their winter dress, 

 the cases differ from those given under Classes I. and III. 

 only in the characters originally acquired by the males dur- 

 ing the breeding season having been limited in their trans- 

 mission to the corresponding season. When the adults have 

 a distinct summer and winter pluniage, and the young differ 

 from both, the case is more difficult to understand. We 

 may admit as probable that the young have retained an 



** I am indebted to Mr. Blyth for information as to the Buphus ; see, also, 

 Jerdon, "Birds of India," vol. iii. p. 749. On the Anastomus, see Blyth in 

 "Ibis," 186?, p. 173. 



" On the Alca, see MaogiUivray, "Hist. Brit. Birds," v. 347. On the 

 PringSla leucoph/rys, Audnbon, ibid., ii. p. 89. I shall have hereafter to refer 

 to the young of certain herons and egrets being white. 



« "History of British Birds," voL i., 1839 p. 159. 



