PREFACE. 
This classification of the families and genera of bats, primarily 
based on skeletal and dental characters, is chiefly the result of my 
studies of the collections in the United States National Museum. 
During two visits to Europe I have, however, been permitted with 
the utmost liberality to examine the material in the museums of Lon- 
don, Paris, Leiden, and Berlin, with the result that members of prac- 
tically all the known genera of Chiroptera have passed through my 
hands.® To the authorities of these institutions I take pleasure in 
acknowledging my indebtedness. I am also under special obligations 
to Mr. Oldfield Thomas for the unique facilities that I have enjoyed 
for working in the British Museum, and to Mr. Knud Andersen for 
his unfailing kindness in verifying special characters in the specimens 
in London. Finally, to my assistant, Dr. Marcus W. Lyon, jr., 
acknowledgment is due for his care in superintending the drawing 
of some of the illustrations and assistance in reading proof during 
my absence from Washington. 
The pen drawings in the text are mostly by Miss Mary Mason 
Mitchell and the late Dr. J. C. McConnell; those in Plates XI to 
XIY are also by Doctor McConnell. The wash drawings of the 
teeth, forming Plates I to X, were made under my supervision by the 
late Mr. F. van Iterson. They should be regarded as semidiagram - 
matic. 
Owing to the fragmentary condition of the remains by which they 
are known, it has not seemed expedient to attempt to introduce the 
extinct genera in a system based on characters which the fossils have 
for the most part lost. It has also seemed inexpedient to deal with 
subgenera at a time when the species of bats are still very imperfectly 
known. 
All questions of nomenclature have been decided in accordance 
with the Code of Nomenclature of the American Ornithologists’ 
Union, pending the final adoption of an international code. 
Gerrit S. Miller, Jr. 
a Cormura, Stenoderma. and Amorphochilus are the only genera among the 173 
here recognized that I have not seen. 
