Excerpt from Science Bulletin, 1928, Vol. 18: Nos. 1 to 13 The writer wishes to express her appreciation to all those who have assisted in the preparation of this paper. She is deeply indebted to Dr. P. B. Lawson, under whose direction the paper was prepared, for the many tedious hours he has spent in instruction and criticism, at the sacrifice many times of his own research, as well as for the stimulus and inspiration he has given her in completing the paper. The writer is under special obligation to Dr. E. D. Ball for the material which he has so generously supplied whenever it was called for, and for the helpful suggestions he made in regard to various forms. Likewise she is indebted to the following workers for very kindly loaning her their material: Prof. H. C. Severin, Dr. W. J. Baerg, Dr. L. A. Stearns, Dr. C. J. Drake, the curators of the American Museum of Natural History and the United States Na tional Museum, and to Dr. E. P. Felt for the opportunity to study the Fitch types at the New York State Museum. Lastly she wishes to thank the following: Dr. H. B. Hungerford for his interest and help in the preparation of the paper, as well as for the extensive collecting which he, assisted by Mr. Charles Martin and Mr. Edward Becton, did in this group in Michigan; also Dr. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.