A LIST OF THE GENERA AND FAMILIES OF MAMMALS. 1] 
genera of birds, fishes, crustacea, insects, etc., have been examined, 
and Seudders * Nomenclator? has been systematically examined at 
least twice for names in other groups which might preoccupy those of 
mammals. In short, no effort has been spared to render the list as 
complete and accurate as possible. 
In August, 1894, the Department acquired from Mr. F. H. Water- 
house, librarian of the Zoological Society of London, a manuseript 
list of genera of mammals prepared on the same plan as his ‘Index 
Generum Avium' published in 1889. This manuscript was generously 
offered to the Department by the author upon his learning that an 
index similar in plan to his own, but somewhat broader in scope, was in 
course of preparation. This offer was at once accepted, and the list 
was found to contain 3,009 names accompanied by references to place 
of publication, while the Department list at that date contained 2,604 
names, of which 2,848 had been verified. Beside 77 new names and 
104 earlier references, many additional important secondary references 
were furnished by the Waterhouse list, but its greatest value lay in 
the check which it afforded on the whole work. It is interesting to 
note the close agreement in these two lists, independently compiled 
(each author being ignorant of the work undertaken by the other). 
Not only were practically the same names found in the two lists, but 
the references in most cases coincided exactly, and are, therefore, more 
trustworthy than if brought together by one individual. 
While it was obviously impracticable to verify references so numer- 
ous and so widely scattered after the list was in type, as was said to 
have been done in the case of Bronn's celebrated Index, certain checks 
were used during the preparation of the work which eliminated many 
errors. The names were arranged on cards, typewritten to secure legi- 
bility and to avoid errors in spelling. Nearly all the references were 
verified independently by two persons, and many of the cards after- 
wards looked over by a third. Notwithstanding these precautions, 
many errors have undoubtedly crept in. In fact, with 4,500 names, 
most of which are accompanied by from six to twelve distinct items of 
information, not to mention the thousands of figures referring to vol- 
umes, pages, and years under the references, it can readily be seen that 
the possibility of error is very great. It is hoped that with the checks 
above mentioned, and especially with the acquisition of Waterhouse’s 
manuscript, comparatively few names have been overlooked and that 
few errors will be detected in the references; but in statements regard- 
ing types and classification absolute accuracy is unattainable, owing to 
the variety of ways in which genera have been proposed and the diver- 
sity of views held by leading systematists as to the position of many 
genera or even families. 
At first an attempt was made to fix the type of each genus, but this 
proved impracticable and the plan of including all the species men- 
