Vol. XIX"! Recent Literature. Wl 



1902 J O 



"accurate representations of actual feathers" from this bird, taken, how- 

 ever, in each case, he says, "from different birds, and that I have no proof 

 of the pattern on any individual feather being changed as some writers 

 {cf. R. B. Sharpe, P. Z. S. 1873, p. 44) have suggested : it may be so, or it 

 may not, but that contingency has not been taken into account in this 

 paper." 



He sets out with the hypothesis that "the most primitive feathers 

 were entirely colourless, or of a dull dingy grey, the first trace of a pattern 

 being a longitudinal stripe of colour down the rachis. Possibly the feath- 

 ers of some species become self-coloured without undergoing any pattern 

 stage, but this is doubtful; and in the majority of self-coloured birds, even 

 when white, the self-colouration has been subsequently assumed. The 

 self-coloured feathers are those in which it is most difficult to fix the period 

 of evolution. . . ." There is much more in this line, but Mr. Bonhote fails 

 to tell us how we are to distinguish ' self-coloured feathers,' or in what 

 the process of 'self-colouring' consists, whereby, apparently, a striped or 

 barred feather may become white, or of some uniform dark shade. Evi- 

 dently he still believes in the increase, or decrease, or entire rearrange- 

 ment of pigment within the grown feather; but even from this point of 

 view we fail to see how he has thrown any real light on the evolution of 

 the pattern of feathers. 



The facts in the case are : in birds which undergo a series of changes 

 in color, in passing from first to mature plumage, there is often, or usu- 

 ally, a color pattern in the young bird very different from that of the 

 adult, with sometimes intermediate stages different from either. If the 

 same feathers were worn throughout these changes there would be some 

 basis for a theory of "evolution of pattern in feathers" ; or rather, there 

 would be no need of any theory at all, for the evolution would be a mat- 

 ter of simple aud easy observation. As a matter of fact, however, such 

 an evolution of pattern is impossible; the Juvenal plumage of a bird, with 

 its particular pattern of markings, is one thing ; the postjuvenal, with a 

 different pattern is another; and so on with subsequent plumages till the 

 mature pattern is reached. Each moult may give a different pattern from 

 that of the plumage which preceded it. How then can we say that a 

 barred type of feather, or a whole-colored feather is 'evolved ' from a lon- 

 gitudinally striped one, with any regard to the strict meaning of the term ? 

 On the other hand, in certain birds of varied plumage, it is possible to 

 select feathers from different parts of the body of the same individual 

 which will show not only wholly distinct patterns, but also every inter- 

 mediate stage connecting the two, feathers of a certain type or pattern 

 always being characteristic of a certain part of the pterylosis and other 

 types or patterns of other parts of the pterylosis. Furthermore, these 

 different types or patterns are not successional but are all developed at 

 the same time, each in its respective position in the pterylosis. Yet, in 

 certain instances, a series may be plucked from different pftrts of the 

 same bird, some of which will have simply a narrow stripe along the 



