VI PREFACE. 



The material used in revising the okl monograph and bringing it up 

 to date is for the most part that in the possession of the U. S. National 

 Museum. Valuable aid was received by specimens examined from the 

 collection of the Museum of Comparative Zoology of Harvard Uni 

 versity; that of the American Museum of Natural History, I^ew York; 

 that of the Academy of Natural Sciences of Philadelphia ; and that of 

 the California Academy of Science. I desire to return my thanks to 

 the officers of these institutions for courtesies extended. Dr. C. Hart 

 Merriam, of the Agricultural Department, Washington, kindly sent me 

 the entire valuable collection of the Vei^pertiUo in his charge; and by 

 so doing enabled me to study this difficult genus under the most favor- 

 able circumstances. Special acknowledgments are also due Mr. H. A. 

 Ward, of Rochester, N. Y., who placed in my hands his entire collec- 

 tion of Chiroptera. I also wish to thank Mr. G. S. Miller, jr., of Cam- 

 bridge, Mass.; Prof. J. H. Montgomery, of Meadville, Pa., and Dr. 

 Robert W. Haynes, of Los Angeles, Cal., for vaUiable assistance. 



All measurements are assumed to be in the French scale unless other- 

 wise stated. 



The measurements in English scale are taken from the monograi)h 

 of 1864, together with lists of specimens which at that time formed the 

 basis of the descriptions. These are copied for the convenience of 

 readers who may not have access to that publication. 



The figures have been drawn by Mr. F. von Iterson with a fidelity 

 to the originals which can not fail to aid the student of a confessedly- 

 difficult group of animals. 



ABBREVIATIONS. 



U. S. N. M. — United States National Museum. 



A. N. S. P. — Academy of Natural Sciences of Pliiladelphia. 



M. C. Z. — Museum of Comparative ZoiJlogy. 



