868 Mr. C. Tiigrara on the [Ibis, 



and certain otlier species (i. e., Barbels, Toucans, and Wood- 

 ])cckers) have aire, dy been connnented npon by other writers, 

 and I thinlc Pycraft's interpretation of their use — namely, to 

 protect the young bird from injury in its nnlined nest- 

 cavity — is und(.ubtedly a correct one *. It is interesting to 

 note thut incipient heel pads may also be detected in 

 newly-hatched specimens of the ('ommon Starling [Sturnns 

 vulyaris\ 



Besides those already mentioned elsewhere, neossoptdcs 

 are wanting in s(.>me, or in all, the species of the following 

 genera: — Hypolais, Acrocephulus^ Sylvia, Garrulus, Punurus, 

 and Cuculus. As the young of most of tliese are reared in 

 open nests and some of the species are small and feeble, the 

 com[)lete disappearance or non-development of a procryptic 

 nestling plumage is somewhat difficult to explain. 



At one time I thought the Shrikes (Laniidie) were also 

 destitute of neossoptiles when hatched, but quite recently 

 I discovered small pre-pennte in four- or five-day-old 

 specimens of the lied-backed Shrike. Apart from very 

 degeneiate and insignificant down on the tij)s of the main 

 wing-feathers tliese prc-pennie were confined to the postei'ior 

 third of the ventral tract, and were attached to seven or 

 eight of the teleoptiles forming the median row of that 

 tract (tig. 16). I do not know of any other birds with a 

 similar down-pytery losis. 



Fig. 10 illustrates the remarkable variation in nestlings 

 that may (jccur within the limits of a single family. Jt 

 will i)e noted, iiowever, that most of these difi'erences are 

 consist nt with the theories and explanations given above. 

 The Carrion-Crow {Corvus curone), building in more or less 

 elevated positions, has its nestling well furnished with 

 greyish- white down. With the Rook [C. fruyiiegus) there 

 is less necessity for concealment, as the bird breeds in 

 colonies. Consequently the neossoptile plumage has de- 

 generated somewhat and is now completely absent from the 



* I'eebe ('Tropical ^^'il(l Lift') describes ;inJ figures the nestling 

 Ariciui Touciiii {Picroijlossus aricari). TJie vounn^ of this species lias very 

 ^veil-developed lieel-puds. Upon these and the hind ])art of the body they 

 apparently rest " with their feet and toes held up helplessly in mid-air.'' 



