640 PROF. J. COSSAR EWAUT ON THE 



Edinburgh and a grant has been voted from the Carnegie Trust 

 for the Universities of Scotland, towards the cost of publishing 

 this joaper. 



In addition to material in the form of ducklings, goslings &c., 

 bred at Craigybield, Penicuik, it ought to be mentioned that 

 valuable contributions for the study of nestling feathers were 

 provided by the Director of the Zoological Society of Scotland, 

 and that but for the Institution of the Scottish Zoological Park 

 I would not have been led to undertake research work on the 

 Structure and History of Feathers. Purther, it ought to be 

 mentioned that during the investigation I received valuable 

 material fi'om the Zoological Society of London, the Royal 

 Scottish Museum, and the Philosophical and Literary Institute 

 of Leeds, and that I am especially indebted for specimens that 

 proved most useful to Colonel Ashley, M.P., Miss Clerk of 

 Penicuik, William J. Gordon, Esq., of Windhouse, Yell, 

 Shetland, Professor Meakins, the TJnivei'sity of Edinbm^gh, 

 and Professor Philip J. White, the University of North Wales. 



References to Literature cited in Paper. 



1. Ingram, Collingwood. — 'The Ibis,' October 1920, p. 856. 



2. Gadow, Hans F. — Newton's ' Dictionary of Birds,' p. 243. 



3. Pycraft, W. p. — "The Emperor and Adelie Penguins," Nat. 



Ant. Expedition, Zoology, vol. ii. p. 12. 1907. 



4. Owen, R. — Comparative Anat. vol. ii. p. 235. 



5. NrrzscH. — ' Pterylography,' English Translation, p. 8. 1867. 



6. Gadow, Hans F. — Newton's ' Dictionary of Birds,' p. 245. 



7. Degen. — Trans. Zool. Soc. vol. xvi. pp. 362 & 363. 



8. Pycraft, W. P. — Trans. Zool. Soc. vol. xv. p. 164. 



9. ,, „ Nat.Ant. Expedition, Zool. vol. ii. pp. 7 & 8. 



10. Nopcsa.— Proc. Zool. Soc. 1907. 



11. Lull.—' Organic Evolution,' pp. 533 & 534. 1917. 



12. Pycraft.—' A History of Birds,' p. 39. 1910. 



13. Bornstein. — Archiv f. Naturgesch., Band I. Supplement, 



heft 4. 



EXPLANATION OF THE PLATES. 



Pj:.A.TE T. 

 Pig. 1. Protoptile and metaptile from vicinity of preen gland of a 38 days' 

 Mallard. The mesoptile lias been suppressed. The long barbs proceeding 

 from the inner aspect of the protoptile calamus towards the calamus of 

 the metaptile are vestiges of a metaptile aftershaft. X 2. 



2. Protoptile, mesoptile, and tip of a wing-quill of a 5 weeks' Indian llunner 



duckling. 



3. Protoptile, mesoptile, and tip of a wing-covert of a 6 weeks' Emden 



gosling. 



4. Tip of tail-quill of a young Ringed Penguin (n. s.). 



•Plate II. 

 Pig. 5. Tail-quill and protoptile of a 5 weeks' Mallard duckling (n. s.). 



6. A 10 days' Mallard embryo. The tail-quill papillae are well developed, but 



there is little indication of the wing-quill papillae. 



7. Wing of a 25 days' Mallard duckling showing the wing-quill protoptiles (n. .s.). 



8. Wing-quill protoptile from a live weeks' Mallard duckling attached to tip 



of developing mesoptile. 



