A LIST OF THE GENERA AND FAMILIES OF MAMMALS. T9 
the authority by whom they were first published. Misprints and 
emendations are sometimes given in the form * Ao/us (A. Smith) Gray? 
in order to connect the changed spelling with the original name. 
LOCALITIES. 
In modern systematic work the statement of the type locality of a 
species is considered almost as important as the reference to the origi- 
nal description. An attempt has been made, therefore, to give such 
information as 1s available concerning the locality of the type species 
of each genus, but with only fairly satisfactory results. In the case of 
genera based on American species, and especially those based on North 
American species, the type localities are usually stated with some degree 
of precision; but in the case of genera based on Old World species the 
statements concerning localities are often indefinite and may consist 
simply of the name of the country or the region in which the species 
is known to occur. In the case of extinet groups the statement may 
mention simply the bed or formation in which the remains have been 
found, but to readers familiar with the paleontology of the region this 
will often be clearer than reference to the nearest town, river, or 
mountain. The statement, if any, concerning the locality in the 
original deseription has been generally followed unless too indefinite 
or known to be erroneous, but subsequent information has been freely 
used in throwing light on obscure type localities. Not only have the 
places been given with as much precision as possible, but they have 
been looked up and, when necessary, enough explanation has been 
added to facilitate finding most of them on any good, modern map. 
While much remains to be done in determining the exact localities 
from which species have been described, particularly in the case of 
Old World mammals, the statements given are as complete as the 
information at hand would permit. 
TYPES AND THEIR DETERMINATION. 
Great importance was formerly attached by some zoologists to the 
definition of a genus, and the late Prof. Cope even went so far as 
to declare that a genus proposed by merely naming the species on 
which it was based (a *typonym') was not entitled to recognition. But, 
as Dr. Gill explains: “ 
The demand in such case is simply that the definition shall be made. It may 
be inaccurate or not to the point; it may be given up at once, and never adopted by 
the author himself afterwards, or by anyone else. Nevertheless, the condition is 
fulfilled by the attempt to give the definition. . . . Certainly it is more rational to 
accept a typonym than to require a definition for show rather than use. Neverthe- 
less, I fully recognize the obligation of the genus maker to indicate by diagnosis, as 
well as type, his conception of generic characters. 

4Proc. Am. Ass. Adv. Sci., XLV, 1896, sep., pp. 20-21. 
