specimens. The dearth of such collections, both of ants and of all
other groups of insects, excepting, perhaps, the Coleoptera and Lepi-
doptera, has not ceased to be a great drawback to the study of ento-
mology in America.
The bibliography (Appendix E), which has been carried down to
the close of the year 1908, is unfortunately very voluminous and includes
many titles of unimportant works. Like all such compilations, it is
necessarily incomplete, and undoubtedly contains positive errors. A
serious attempt has been made, however, to reduce these to a minimuia,
and I shall be glad to receive any additions or corrections.
For portions of the text and many of the figures I have drawn
rather freely on my previously published papers. A few entire chap-
ters, in fact, such as those on polymorphism, have been reproduced
with only slight verbal alterations. Others, like Chapters XVIII and
XX, are abridgments of longer accounts of the fungus-growing and
honey ants recently published in the Bulletin of the American Museum
of Natural History.
I am under lasting obligations to Professor H. C. Bumpus for the
interest he has shown in the progress of my work, and the aid which
I received in its prosecution while I was Curator of Invertebrate
Zoology in the American Museum of Natural History. To Wr. Roy
W. Miner, Assistant Curator of Invertebrate Zoology in that institu-
tion, I am deeply indebted for much assistance in making out the table
of contents, and especially in arranging and verifying the bibliography.
Jany of the illustrations have been made by Miss Ruth B. Howe.
Vy friend, Professor Oliver S. Strong, of Columbia University, has
most generously permitted me to use a number of the remarkable
photographs which he and Mr. J. G. Hubbard took of living colonies
of various ants in the possession of Miss Adele M. Fielde. Three of
my former pupils, Messrs. A. L. Melander, C. T. Brues and C. G.
Hartman, have also contributed several interesting figures, and Mr.
Brues has aided me in reading the proof.
Forest Hills, Boston, Mass.,
October 30, 1909.