NESTLING FEATHERS OF THE MALLARD. 611 



of true down ; by the pigment they contain they help to make 

 the duckling inconspicuous. 



(1) The Wing-Quill FrotoptileH. 



Though Ducks have been living under domestication for well- 

 nigh two thousand years, their nestling feathers have appai'ently 

 never been systematically examined. That no serious attempt 

 has been made to study the nestling feathers of ducks and other 

 Anseres, and of fowls and other Galli, is made evident by a 

 perusal of Mr. Pycraft's important monograph on the Emperor 

 and Adelie Penguins. In an interesting chapter on the com- 

 position and sequences of the neossoptiles, after pointing out that 

 " the penguin must certainly be regarded as having preserved 

 what must be looked upon as a somewhat, perhaps very, ancient 

 succession of plumages," Mr. Pj'^craft states that " in the light of 

 my I'ecent discovery " it is clear that the " down " feathers of the 

 Galli and Anseres "do not, as I imagined, represent a primitive 

 type of down feather homologous with the woolly, and so pre- 

 sumably degenerate down of say the Alcida?, but answer to 

 mesoptyles. The protoptyle or first generation of feathers would 

 seem to be wanting in these birds, but I had the good fortune to 

 discover small tufts of down adhering to the tips of the meso- 

 ptyles of a young Chlo'&phaga rubidicejjs. Thus we may assume 

 that this first genera,tion, since it has not yet been traced, has 

 been lost in all the Galli, and probably all the Anseres save 

 perhaps this species and one or two allied genera" (3). 



As PI. I. figs. 2 & 3 show, I have succeeded in tracing two 

 generations of nestling feathers in the Indian Runner Duck and 

 in the common Domestic Goose, and thereby have proved that 

 the coat worn by newly-hatched Ducks and Geese consists of 

 proto])tiles corresponding to the first or protoptile nestling coat 

 of Penguins. In the case of the King Penguin the first or 

 protoptile coat is apparently in the act of disappearing ; but in 

 all the Anseres and Galli I have examined it is the second coat 

 that has' been lost or is in the act of disappearing. Though in 

 the wings of some Ducks and Geese well-developed mesoptiles 

 still make their appearance, the tail-quill mesoptiles are either 

 vestigial or have been completely suppressed. That the pro- 

 toptile is in the act of disappearing in the tail of the Penguin is 

 suggested by PL I. fig. 4, while PI. II. fig. 5 clearly indicates 

 that as the mesoptile was suppressed in the tail of the Mallard 

 the protoptile was enlarged. 



With the help of a prematurely developed "nestling tail" the 

 Mallard duckling begins to dive at the end of the second week, 

 but, owing to the development of the wings being retarded, flying- 

 only becomes possible at the end of the eighth week. That the 

 development of the wing is from the outset retarded is suggested 

 by PI. II. fig. 6, a ten days' duck embryo. In this embryo the 

 papillae which deA'elop into the tail-quill protoptiles are large, 



