270 A HISTORY OF BIRDS 



two of the more primitive Geese, e.g., Clcephaga, ■a. precisely 

 similar sequence obtains, but the second generation of down 

 feathers are here of a more typical feather-like structure, show- 

 ing a well-deyeloped shaft, bearing a number of paired branches 

 or rami. These, later, are succeeded by the " definitive feathers ". 

 Now the down feathers of the Game-birds answer to the feathers 

 of the second generation of the Penguin and those primitive 

 Geese. In some of the Tinamous, e.g., Martineta Tinamou 

 {Caladromus elegans), the down feathers yet more closely re- 

 semble definitive feathers. Consequently, we may infer that 

 these two generations of down feathers represent degenerate 

 plumages, while in some, or rather most species, one — the first 

 ■ — -has become entirely suppressed. This view is the more prob- 

 able since among the Owls, for example, two generations of 

 feathers precede the typical adult feather as in the Tawny Owl, 

 while in the Barn Owl only one is developed. The down 

 feathers of the,Tinamous answer to those of the second genera- 

 tion. In the Megapodes the down feathers of the first genera- 

 tion are extremely degenerate in structure, and are shed before 

 the bird leaves the shell. At hatching it is clothed in feathers 

 of the second generation. From the varying degrees of degener- 

 acy which the feathers of the second generation display, 

 especially among the Game-birds — ^as in the Turkey and 

 Grouse, for example — we may infer that those of the first 

 generation were of a higher type than in any modern bird, 

 though they probably never attained the perfection seen in the 

 contour feathers of living birds. If this is so, then we have 

 in nestling birds to-day another of the many relics of past 

 conditions which a study of life history reveals. But as yet 

 there appears to be no clue obtainable as to the meaning of this 

 degeneracy in the earlier plumages, unless, indeed, it be that 

 each represents a distinct phase, not so much after all in the 

 structural perfection of the feathers, as of coloration ; for it is a 

 curious fact that, as has already been pointed out, and as we shall 

 have occasion to remark again, this nestling plumage, when 

 not of a monotone, is striped or marked with mottlings obvi- 

 ously derived from stripes, and stripes in the plumage of adult 

 birds are rare. Thus it may be that, for reasons not yet 

 apparent, these suppressed down-plumages may represent so 

 many eliminated, because injurious, colour-phases. 



