10 INDEX GENERUM MAMMALIUM. 
(11) derivation, and (12) in some cases the application of the name. 
These facts, while comprising the essential data in regard to a given 
name, are of little assistance in ascertaining what names have been 
used for a particular group and which one of several proposed is 
entitled to recognition. To supply this information the names have 
been arranged alphabetically under orders and fariilies, each one 
accompanied by a statement of the authority, date, type or included 
species, and locality. It is thus possible to tell at a glance all the 
names which have been used in each family, the dates when they were 
proposed, the species on which they were based, and approximately 
the localities of these species.^ In preparing this part of the work it 
became necessary to collect family and subfamily names, only a few of 
which had been previously indexed systematically. "The work there- 
fore consists of 3 parts: (1) an alphabetical index of genera giving the 
essential facts in regard to each name; (2) an alphabetical index of 
families and subfamilies, showing the authority, place and date of pub- 
lication, and the order to which the name belongs; (3) a systematic 
index showing the generic names which have been proposed in each 
family, with the more important facts regarding authorities, dates, 
and types. 
The present index was projected by Dr. C. Hart Merriam about 
1884 and was intended at first to include merely the genera of living 
mammals with the exception of the cetaceans. When undertaken by 
the present writer in November, 1889, it contained about 250 names. 
Two years later a systematic examination was made of Scudder's 
‘Universal Index,’ the * Zoological Record’ for 1878-91, and general 
works on mammals, and the names thus obtained, accompanied only 
by authority and date, were arranged alphabetically in a skeleton list 
on the plan of Scudder’s Index. Additional names were entered in 
this list from time to time and the references looked up and verified 
at the first opportunity. At the close of 1891 the number of genera 
verified was about 375; on January 1, 1893, it had increased to about 
650; on January 1, 1894, to 2,045; on January 1, 1895, to about 3,300; 
on January 1, 1896, to 3,850; on January 1, 1897, to 3,900; on Janu- 
ary 1, 1898, to about 4,275; on January 1, 1899, to 4,318; on January 
1, 1900, to about 4,400; and on July 1, 1902, to about 4,500. As the 
work progressed it was decided to change the plan so as to include all 
recent genera, and finally to make it complete by indexing extinct 
genera. Not only works on mammals but general serials and books 
of reference have been examined for names. Several indexes of 

* ]t will be observed that no attempt is made to distinguish synonyms from valid 
names except in case of preoccupation. Such information must be sought in special 
monographs or works like Trouessart’s ‘Catalogus Mammalium.’ The data given 
in the following pages are merely the raw material which will assist the specialist 
engaged in revising a group to select the names he considers entitled to recognition. 
