Chap. XVI.] INHERITANCE, LIMITED BY AGE. 177 



the young have their breasts spotted — a character which 

 is retained by many species throughout life, but is quite 

 lost by others, as by the Tiirdus migratorius. So, again, 

 with many thrushes, the feathers on the back are mottled 

 before they are moulted for the first time, and this charac- 

 ter is retained for life by certain Eastern species. The 

 young of many species of shrikes (Lanius), of some wood- 

 peckers, and of an Indian pigeon {Chalcophaps Indicus), 

 are transversely striped on the under surface ; and certain 

 allied species or genera when adult are similarly marked. 

 In some closely-allied and resplendent Indian cuckoos 

 (Chrysococcyx), the species when mature differ consider- 

 ably from each other in color, but the young cannot be 

 distinguished. The young of an Indian goose {Sarkidior- 

 nis melanonotus) closely resemble in plumage an allied 

 genus, Dendrocygna, when mature.' Similar facts will 

 hereafter be given in regard to certain herons. Young 

 black grouse {Tetrao tetrix) resemble the young as well as 

 the old of certain other species, for instance, the red grouse 

 or T. Scoticus. Finally, as Mr. Blytb, who has attended 

 closely to this subject, has well remarked, the natural 

 affinities of many species are best exhibited in their im- 

 mature plumage ; and, as the true affinities of all organic 

 beings depend on their descent from a common progenitor, 

 this remark strongly confirms the belief that the immature 

 plumage approximately shows us the former or ancestral 

 condition of the species. 



Although many young birds belonging to various or- 



1 In regard to thrushes, shrikes, and woodpeckers, see Mr. Blyth, in 

 Charlesworth's 'Mag. of Nat. Hist.' vol. i. 1837, p. 304; also foot-note to 

 his translation of Cuvier's 'R^gne Animal,' p. 159. I give the case of 

 Loxia from Mr. Blyth's information. On thrushes, see, also, Audubon, 

 ' Ornith. Biography,' vol. ii. p. 195. On Chrysococcyx and Chalcophaps, 

 Blyth, as quoted in Jerdon's ' Birds of India,' vol. iii. p. 485. On Sar- 

 kidiornis, Blyth, in 'Ibis,' ISO'J, p. 1*75. 



