246 University of California Publications in Zoology Vou. 138 
II. AcKNOWLEDGMENTS 
To Professor C. A. Kofoid, of the University of California, under 
whose direct supervision this work was carried on, the writer is 
especially grateful for his very valuable advice and suggestions, 
and for his aid in the preparation of this paper. 
The writer is indebted to Dr. Joseph Grinnell, of the Museum of 
Vertebrate Zoology of the University of California, for free use of 
the specimens in the museum. He also wishes to express his appre- 
ciation of the generous supply of material for study by the American 
Museum of Natural History in New York, and the United States 
National Museum in Washington. Grateful acknowledgments are 
due to Dr. W. T. Hornaday and Mr. Lee 8. Crandall of the New 
York Zoological Park for saving and sending molted feathers which 
could not readily be procured from museum specimens. 
Other material was procured from the Memorial Museum in 
Golden Gate Park, San Francisco, through Mr. W. G. Blunt of 
the Natural History department. The writer is further indebted 
to the California Academy of Sciences in San Francisco, for the use 
of its collection of water birds, and to the Bentley Ostrich Farm of 
Oakland, California, for the supply of ostrich feathers, and assist- 
ance in the examination of living birds. 
Ill. Huisrorican 
The first thorough and reliable work on feathers was done by 
Nitzsch, a German ornithologist. This work was edited and pub- 
lished by Burmeister, and later translated into English and published 
in the Transactions of the Ray Society in 1876, a few of the miscon- 
ceptions of the original author being rectified in the process. 
This work, though dealing primarily with pterylography, contains 
the first approximately accurate account of the structure of feathers 
to be found in the whole literature of the subject, and may justly 
stand as a masterpiece. Following Nitzsch, a number of works on 
the development and structure of feathers appeared, among which 
may be mentioned especially Clement (1876), Studer (1878), Jeffries 
(1884), Klee (1886), Davies (1889), and Strong (1902) ; and, more 
particularly on structure, Wray (1887b), Pyeraft (1893), and 
Mascha (1904). Many other less general but highly valuable papers 
