514 Jonathan Dwight, Jr. : 



International Ornithological Congress, of salient facts that 

 have gradually come to light in the years that have elapsed 

 since the study of birds has passed beyond the realm of 

 conjecture. These are matters that concern ornithologists 

 the world over, and it is to be hoped the day will come when 

 some degree of uniformity in the terminology of plumages 

 and moults may be attained. My efforts have been only 

 a step in this direction, and I have now prepared a table 

 which shows, at least, the relation in which plumages and 

 moults stand, the terms applied being those that I have 

 found to be appropriate and worthy substitutes for the lax 

 expressions that pass current. 



It will be seen on reference to my table that there are two 

 stages of plumage peculiar to all young birds, the natal and 

 the juvenal, which are always simple. Later plumages may 

 be either simple or compound, those of the first year being 

 more complicated than those of the second owing chiefly to 

 the incompleteness of the post-juvenal moult in many species. 

 The third and later years duplicate the second. 



In earlier papers * I have discussed at some length the 

 various plumages and moults, but a brief review here, even 

 at the risk of repetition, may not be amiss in order that we 

 may better get at the facts. I shall therefore sketch the 

 successive stages of plumage, and show how they are affected 

 by moults. 



The first is the natal plumage or down (ptilosis natal is), a 

 rudimentary plumage of rudimentary feathers, the neosso- 

 ptiles, which are the modified tips of the feathers of the 

 succeeding generation. As the neossoptiles are constricted 

 into a rudimentary calamus, and as they break off at this 

 point when the natal plumage is shed, it is proper, I think, 

 to consider the process of loss as a rudimentary moult. This 

 plumage may also develop in two stages, for Mr. F. M. 



1 "The Sequence of Plumages and Moults of the Passerine Birds of 

 New York.'' Annals N.Y. Acad. Sci., XIII., 1900, pp., 73-860, pll. i-vii ; 

 "The Moult of the North American Tetraorndse " (Quails, Partridges and 

 Grouse). Auk, XVII., 1900, pp. 34-51, 143-166, pll. iv., v ; "The Moult 

 of the North American Shore Birds" (Limicolse). Auk, XVII., 1900, 

 pp. 368-385 ; " Plumage-cycles, and the Relation between Plumages and 

 Moults." Auk, XIX., 1902, pp. 248-255. illust. in text. 



