144 Zoologica: N. Y. Zoological Society. [I; 5 



Normally Physiologically 



Trimmed Denuded 



Rectrices, Rectrices, 



Removed Jan. 14, Removed Oct. 1, 



1909. 1909. 



Left. Right. Left. Right. 



Outer webs — 



Racket, length 52 51 50 51 



Bare shaft, length 19 23 26 26 



Inner webs — 



Racket, length 54 55 54 55 



Bare shaft, length 21 22 19 22 



As will be seen, the differences in the two sets of feathers 

 are so slight as to be negligible. The only distinction is in the 

 neatness — the physiologically denuded areas are clean-cut to the 

 limits, while in the bird-trimmed feathers, stray barbs are left 

 here and there near the ends of the bare area. Such a difference 

 is interesting and to be expected. 



Although it has been so stated by a number of recent 

 writers,* I can find no authentic account of the voluntary denu- 

 dation of its elongated central tail feathers by the Racket-tailed 

 Parrot, Prioniturus platurus, an inhabitant of the East Indian 

 island of Celebes. On the contrary the bird seems to have 

 reached, or at least at present exhibits, the stage of physiological 

 denudation — much as in my artificial condition of the Motmot. 



Concerning this bird we read as follows: — ** 



"The specimens in the Dresden Museum prove that the webs 

 are neither rubbed off, nor bitten off as in the case of the Mot- 

 mots Two specimens display the growing racket as found 



underneath the upper tail-coverts; the shaft is already webless 

 even where it is still enclosed in the corneous husk or follicle out 

 of which the young feather has grown and where it could of 

 course be neither rubbed nor bitten. On removing a third 

 younger sprouting racket by the root and taking off the epider- 

 mal husk it was found that the web is present on either side of 

 the shaft, but some of the rami appear not to be attached at all 

 but to run, soldered together, parallel to the shaft almost to its 

 roots; other rami have become individually broken off or have 

 fallen off from the shaft, and it was easy to see that, as the 

 feather grew longer, all would have fallen from the shaft. In a 

 growing racket with the shaft 35 mm., cut out of the tail of an 

 adult male bird it was not possible to detect any signs with cer- 



*For example, "Through Southern Mexico," Gadow, p. 483. 

 **"Birds of Celebes," Meyer and Wiglesworth, Vol. i, p. 74. 



