A LIST OF THE GENERA AND FAMILIES OF MAMMALS. 0 
sometimes gives the type or included species with the names, but in 
the * Universal Index? he gives merely the authority and date without 
reference, and to find the place of publication it is necessary to con- 
sult previous lists. Trouessart also in many cases gives only authority 
and date. 
Notwithstanding these indexes many names were overlooked, and 
as they were gradually brought to light some of those in current use 
were found to be preoecupied and others antedated. As a result, 
names have been shifted so frequently that it has become very difficult 
to keep pace with the changes, and general readers who do not appre- 
ciate the necessity for such changes regard the desired goal of sta- 
bility as practically unattainable. The extent of these changes is 
clearly shown in the case of North American mammals. Of the 160 
or more generic names used by True in his ‘Provisional List of the 
Mammals of North and Central America, in 1885, some 35 or 40, 
or nearly 25 per cent of the entire number, have been changed during 
recent years on what may be termed bibliographical grounds. Ten 
of these names have been found to be preoccupied and the others have 
given way to earlier names. Changes like these can only be avoided 
by having complete indexes which will show not only what names 
have been proposed in a given class and on what species they are 
based, but also whether the same generic names have been previously 
applied to other groups. 
The present index, which differs materially from previous ones in 
containing much information besides the name, authority, and place of 
publication, was undertaken in connection with the systematic work 
on mammals carried on by the Biological Survey, in order to collect 
for convenient reference not only the names given in previous indexes, 
but also those which had been overlooked or which had been published 
since the appearance of these works. Its object is to bring together 
all the generic and subgeneric names” of mammals, both living and 
extinet, which have been proposed since 1758, and to furnish such data 
of a bibliographical nature as to facilitate finding when and where 
each name was published, and to what group it was applied. It gives, 
so far as possible for each name, (1) authority, (2) date of publication, 
(3) order and family, (4) reference to original place of publication, 
(5) important secondary references, (6) variations in spelling, (7) type 
or included species, (8) locality of type species, (9) indication of pre- 
occupation, with cross reference to names, if any, proposed to replace 
them, (10) a statement (if published) of the part of extinct animals— 
as the skeleton, skull, teeth, etc. —which constituted the type specimen, 



* Since it is often merely a matter of personal opinion whether a given group is 
considered as a genus or subgenus, genera and subgenera are here treated alike, 
except that a subgenus is indicated as such and if it has been subsequently raised to 
full generic rank this fact is indicated by a secondary reference. 
