856 Mr. C. Ingram on the [Ibis, 



XXXIl. — A Contribution to the Study of Nestling Birds. 

 By Colling WOOD Ingram, M.B.O.U. 



(Text-figures 1-17.) 



Theke is no brancli of ornithology that lias remained so 

 long neglected as tlie study of nestling birds, nor is there 

 one in which so many problems still await solution. Upon 

 closf! examination, even the young of altricial birds will be 

 found to vary considerably, aud often, within the limits of a 

 single family, they display a really remarkable adaptability 

 to the conditions under which their [)arents breed. The 

 chicks of precocial species are possiijly more interesting, foi' 

 they show still greater vei'satility, especially in regard to 

 the pattern aud texture of their downy covering, but I do 

 not intend to deal with these now. Nor is it my inteutiou 

 to make an exhaustive survey of all my notes on the young 

 of nidicolous species — these have been accumulating for 

 twenty years or more, and have become far too bulky to be 

 adequately condensed into a single paper. The following 

 pages, tiien, must be regarded as only a small contribution 

 to a very fascinating study, aud are ofi'ered chiefly with the 

 idea of stimulating further research. 



As the terminology of plumage does not appear to be very 

 stable and is not yet in common use, it is perhaps advisable 

 to briefly give a few definitions of the terms I intend to 

 adopt : — 



Plumules. — The small downy feathers foimd in the adults 

 of many birds. Plumules may occur either in the apteria, 

 or in the pterylse, or in both ; but in some species they are 

 completely absent. In the adult individual they are normally 

 concealed by the contour-feathers. 



Pre-pennce. — The small dovvny feathei's that precede, and 

 are afterwai'ds replaced by, contour-feathers. These are 

 found in the young of many birds. 



Pre-jj/wnulce. — The small downy feathei's that precede, 



