PREFATORY NOTE xi 
but they have gone out as chapters in forbid- 
ding public documents, or else separately in 
loose pamphlets which in most cases have been 
speedily lost. It is impracticable for the or- 
dinary man to get copies of them now if he 
tries, and their usefulness has therefore come 
to an untimely end. Among them are original 
and valuable essays by Dr. C. Hart Merriam, 
Chief of the Biological Survey until his resig- 
nation in 1910, when H. W. Henshaw succeeded 
to his office; Vernon Bailey, the assistant in 
charge of field investigations; David E. Lantz, 
Wilfred H. Osgood, E. W. Palmer, Stanley E. 
Piper, H. W. Nelson, Edward A. Goldman, and 
others attached to the Department. 
Knowing the accuracy and importance of this 
half-lost material, and also aware that nothing 
better could be furnished in its stead, I have 
not hesitated to make liberal use of it, often 
in its own well-chosen language. It was writ- 
ten for the benefit of the public; and I am con- 
fident the gentlemen above mentioned will 
gladly see it renew its usefulness in the per- 
manent form a bound book affords, and rejoice 
in the greater force their facts and recommen- 
