11 
PREFACE 
colors, but the effort was successful only to the extent that it was 
an improvement on its predecessors; and, although still the 
standard of color nomenclature among zoologists and many other 
naturalists, it nevertheless is seriously defective in the altogether 
inadequate number of colors represented, and in their unscientific 
arrangement. Fully realizing his failure, the author, some two or 
three years later, began to devise plans, gather materials, and 
acquire special knowledge of the subject, in the hope that he might 
some day be able to prepare a new work which would fully meet 
the needs of all who have use for it. Unfortunately, his time has 
been so fully occupied with other matters that progress has neces¬ 
sarily been slow ; but after more than twenty years of sporadic 
effort it has at last been completed. 
Acknowledgments are due to so many friends for helpful 
suggestions that it is hardly possible to name them all, or to specify 
the extent or kind of help which each has rendered; but special men¬ 
tion should be made of Mr. Eewis E. Jeweee, of Johns Hopkins 
University; Dr. R. M. Strong, of the University of Chicago; 
Prof. W. J. Spieeman, of the U. S. Department of Agriculture ; 
Mr. Wieeiams Weech, of the U. S. Signal Service; Mr. Mieton 
Bradeey, of Springfield, Mass.; Dr. P. G. Nutting, of the U. S. 
Bureau of Standards; Mr. P. E. Ricker, of the Bureau of Plant 
Industry, U. S. Department of Agriculture; and Mr. J. E. 
Ridgway, of the U. S. Geological Survey. The late Professor 
S. P. EanGEEY, then Secretary of the Smithsonian Institution, was 
good enough to take a kindly interest in this undertaking and gave 
the author assistance for which he is glad to make acknowledg¬ 
ment. More than to all others, however, is the author deeply 
indebted to Mr. John E. Thayer, of Eancaster, Mass., and Senor 
Don Jose C. ZeeEdon, of San Jose, Costa Rica, for aid so indis- 
pensible that without it the work could not have been completed. 
To Dr. G. GrubeER & Co., of Eeipzig, Germany, the author 
is under obligations for the gift of a nearly complete set of their 
celebrated coal-tar dyes, which have proven quite necessary to the 
work, especially in the coloring of the Maxwell disks on which the 
color scheme is based. 
The reproduction of the plates has been a difficult matter, 
involving not only expensive experimentation, but more than three 
