BIRDS— INHERITANCE LIMITED BY AGE. 459 



allied animals, such as the tapir, are mai'ked with dark longitu- 

 dinal stripes; but here we have a character apparently derived 

 from an extinct progenitor, and now preserved by the young alone. 

 In all such cases the old have had their colors changed in the 

 course of time, whilst the young have remained but little al- 

 tered, and this has been effected through the principle of inherit- 

 ance at corresponding ages. 



This same principle applies to many birds belonging to various 

 groups, in which the young closely resemble each other, and differ 

 much from their respective adult parents. The young of almost 

 all the Gallinacese, and of some distantly allied birds such as 

 ostriches, are covered with longitudinally striped down; but this 

 character points back to a state of things so remote that it hardly 

 concerns us. Young cross-bills (Loxia) have at first straight 

 beaks like those of other finches, and in their immature striated 

 plumage they resemble the mature redpole and female siskin, as 

 well as the young of the goldfinch, greenfinch, and some other 

 allied species. The young of many kinds of buntings (Bmberiza) 

 resemble one another, and likewise the adult state of the common 

 bunting, B. miliaria. In almost the whole large group of thrushes 

 the young have their breasts spotted — a character which is re- 

 tained throughout life by many species, but is quite lost by others, 

 as by the Turdus migratorius. So again with many thrushes, the 

 feathers on the back are mottled before they are moulted for the 

 first time, and this character is retained for life by certain eastern 

 species. The young of many species of shrikes (Lanius), of some 

 woodpeckers, and of an Indian pigeon (Chalcophaps indicus), are 

 transversely striped on the under surface; and certain allied spe- 

 cies or whole genera are similarly marked when adult. In some 

 closely-allied and resplendent Indian cuckoos (Chrysococcyx), the 

 mature species differ considerably from one another in color, but 

 the young cannot be distinguished. The young of an Indian 

 goose (Sarkidiornis melanonotus) closely resemble in plumage an 

 allied genus, Dendrocygna, when mature.* Similar facts will here- 

 after 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. Blyth, who has attended closely to this subject, has well 

 remarked, the natural affinities of many species are best exhibited 



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

 Charlesworth's 'Mag. of Nat. Hist." vol. i. 1837, p. 304; also footnote 

 to his translation of Cuvier's 'Regne Animal,' p. 159. I give the case 

 of Loxia on Mr. Blyth's information. On thrushes, see, also, Audu- 

 bon, 'Ornith. Biography,' vol. ii. p. 195. On Chrysococcyx and Chal- 

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

 On Sarkidiornis, Blyth, in 'Ibis,' 1867, p. 175. 



