PREFACE. vi 
cured for the libraries of this country. In such cases, which are 
not however numerous, I have given the date which I have been 
induced from circumstances to believe correct. 
The arduous task of tracing back each genus to its source, and 
of comparing and estimating the value of synonyma (especially in 
cases where, from the adoption of different principles of division, 
or from the want of any principles at all, it was difficult to form a 
precise idea of the limits of the genera proposed) was an essential 
part of an undertaking, the foundation of which was to be based 
on “the inflexible law of priority.” Acting upon this impartial 
rule, I have not thought it just to follow the practice, adopted by 
many writers, of rejecting names merely because they were un- 
accompanied by characters, when there appeared a sufficient indica- 
tion to determine their proper application. When the “ meaning 
of the author,” says Mr. MacLeay, “is thus in some measure as- 
certained, I may choose not to increase the confusion by refusing 
to adopt them.” Among those, indeed, who have been foremost 
in rejecting such names, few are found to have followed throughout 
the principle which they have themselves laid down. 
So far has the desire of introducing new names been carried, 
that many Ornithologists are in the constant habit of changing ge- 
neric names, even when accompanied by characters, if the slightest 
modification is made in the circumscription of the group to which 
they are applied, or even if the characters do not tally with their 
own idea of sufficiency. ‘Thus, an author will not hesitate to state, 
that he cannot adopt the genera of certain Ornithologists, because 
they are not what he is disposed to consider “ natural divisions;” he 
therefore proposes his own divisions, and designates them by his 
own names. But it is curious in such cases to compare the “natu- 
ral” with the “ unnatural” divisions ; and to observe, in the great 
majority of instances, how nearly they coincide with each other. 
The inutility, or worse, of coining new generic names in such 
cases is obvious to all except the coiner himself, who may perhaps 
fancy that he is increasing the stock of knowledge, while he is only 
overloading the memory with synonymous terms. Such uncalled- 
for changes must necessarily prove detrimental to the progress of 
science, the advancement of which is supposed to be aimed at by 
