UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. I I, No. 13, pp. 329-376, pis. 16-20 March 21, 1914 



MODIFICATIONS AND ADAPTATIONS TO 



FUNCTION IN THE FEATHEES OF 



CIRCUS HUDSONIUS 



BY 



ASA C. CHANDLER 



CONTENTS 



PAGE 



lutroduction 330 



Pterylography 331 



Moults 331 



Down Feathers _ 332 



Ordinary Down 332 



Powder Down 333 



Oil Gland Feathers 334 



Filoplumes 334 



Eemiges 336 



Macroscopic Structure ; 336 



Microscopic Structure 340 



Wing Coverts 344 



Greater Upper Coverts 344 



Greater Under Coverts _ 34.5 



Middle and Lesser Upper Coverts 346 



numerals _ 347 



Middle and Lesser Under Coverts 347 



Alula 348 



Eeetrices 350 



Contour Feathers of the Trunk 352 



Upper Parts 352 



Under Parts 354 



Modified Feathers of the Head 357 



Facial Euflf 357 



Ear Coverts 358 



Post- and Supraorbital Bristles 359 



Eyelashes 359 



Loral and Rictal Bristles 360 



Conclusions 301 



Literature Cited 366 



