1870. | Recent Literature. 313 
synonomical lists involves many nice points in the settlement of 
which it is hardly to be expected there will be an unanimous 
opinion among naturalists, especially when a question of such 
prime importance as to what does or does not constitute a species 
is left practically to each author’s own judgment, and hence, not 
infrequently, its settlement becomes simply a presentment of indi- 
vidual opinions, or merely an exponent of the amount of material 
on hand for comparison. ‘Here our author’s power of. research 
and fine critical ability is well displayed, and we think that in the 
main his conclusions rest upon safe ground. 
In other cases we believe his views will bear scrutiny, and may 
cite, as a possible instance of hasty conclusion on the part of the 
author, his statement that the Petrochelidon fulva, of the West 
Indies, is scarcely, if at all, distinct from our P. /unifrons. We 
are giad to notice that he has left the matter open for future 
investigation and final settlement, as we feel sure that direct com- 
parisons of specimens will show that the two are entirely distinct, 
even on the least conservative grounds. 
But most important of all must be deemed the bibliographical 
appendix which is simply a brief extract of the Universal Bibli- 
ography of Ornithology, which is now in the author’s hands well 
advanced towards completion. 
The student must regret, of course, that within the present 
covers is not contained a full presentation of all North American 
titles, and that the present could not thus be made a monograph 
of this part of the subject. But if the line had to be drawn 
somewhere, he may congratulate himself that he has here access 
to so much as ninety-five per cent. of the whole amount, for so 
large a proportion as this, as the author states, is here represented. 
The missing five per cent. consist of all monographs, all general 
treatises on the birds of larger geographical areas, even if includ- 
ing North America, and all general works on ornithology. 
We miss a few titles that appear to us should be present, even 
under the limitations drawn for himself by the author. Thus we 
do not find Grinnell’s List of the Birds of the Yellowstone 
National Park in Capt. Ludlow’s Report of the Chief of Engineer's, 
1876, and Henshaw’s Report on the Ornithological Specimens of 
the Wheeler Expedition for 1872, 73, ’74, both quartos and of 
considerable importance, as well as some others. But these must 
be looked upon as omissions of but trifling importance when we 
consider the admirable fullness of this bibliography within its 
prescribed limits.: We should not omit to mention that a most 
excellent index, almost, in fact, a bibliography by itself, renders 
reference to any desired title an easy and expeditious matter. 
The bibliography if finished with the same painstaking care so 
evident in this extract, must stand as a monument of critical labor 
and as a model for all future work in the same direction. 
Glancing at the press-work it is evident that much care has 
