, 
164 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
species which are truly or peculiarly North American and those which 
are more properly visitants from other countries; but in the case of 
those whose occurrence appears to be accidental or occasional, the num- 
ber preceding the name is inclosed in brackets. Of the latter class, 
species which there is good reason to believe did not reach our limits 
through natural means (i. e., those escaped from confinement) have been, 
in every case, carefully excluded, as have likewise all introduced species. 
It has been deemed best, in view of the recent discoveries along our 
southwestern border, to retain as North American all the species (less 
than a dozen in number) treated by Professor Baird in Volume IX, 
Pacific Railroad Reports (‘‘ Birds of North America”), and likewise given 
in the old catalogue, on account of their having been obtained just across 
the boundary, in Northern Mexico; their discovery within our limits being 
quite certainly only a question of time and investigation. For the same 
reason, the remaining few of Giraud’s “Sixteen New Species of Texan 
Birds”* are also included. Neither are we prepared to relinquish several 
Audubonian species which at the present time are known only from 
the descriptions and figures by their discoverer (e. g., Regulus cuvieri, 
Perissoglossa |?| carbonata, Dendreca montana, and Wilsonia minuta, as 
well as other better-known species which are given by Audubon on his 
own authority (€. g., Chrysomitris ** magellanica” = C. notata, and Eudoci- 
mus ruber). 
Several species peculiar to the islands of Socorro and Guadalupe, off 
the coast of northwestern Mexico and Lower California, respectively, 
together with the few forms peculiar to the latter peninsula, are re- 
garded as truly North American, their affinities, with perhaps only two 
exceptions (7. ¢., Conurus holochlorus and Polyborus lutosus), being strictly 
“¢ Nearctic.” 
The greatest difficulty encountered in the compilation of this work 
has been in the way of distinguishing between valid “species” and 
those forms to be regarded as geographical races of merely subspecific 
rank. The greatest care has been taken in all doubtful cases of this 
kind, and previous conclusions (published in “ History of North Ameri- 
can Birds”? and elsewhere) carefully reconsidered, with the aid of all the 
material accessible, including many specimens not previously in hand. 
This reconsideration of the subject has, in not a few eases, resulted in a 
reversal of former opinion, specimens from important localities not be- 
fore represented often deciding the point one way or the other. Every 
form whose characteristics bear unmistakably the impress of climatic or 
*A Description of Sixteen New Species of North American Birds, by Jacob P. 
Giraud, jr. New York. George F, Nesbitt, printer, Tontine Building, corner of Wall 
and Water streets. 1841. Folio, not paged, 8 plates. [For species given in this 
work, which have not since been obtained within the limits of the United States, see 
p. 229. ] 
tA History of North American Birds, by S. F. Baird, T. M. Brewer, and R. Ridgway. 
Land Birds. Illustrated by 64 colored plates and 593 woodcuts. 3 vols., royal 4to. 
Boston. Little, Brown, & Co. 
