604 ON SOME NEW FORMS OF AMERICAN BIRDS. 
In var. Mewxicanus the white of throat is more abruptly defined 
against the rufous of abdomen than in var. conspersus, in which 
the transition is very gradual. The latter has the secondaries 
rufous with narrow isolated bars of black; the former has them 
blackish, indented on lower webs with dark rufous. In Mezicanus 
the feet are very stout, and dark brown; in conspersus they are 
much weaker, and deep black. 
All specimens from south of the United States boundary (in- 
cluding Giraud’s type of Certhia albifrons) belong to the restricted 
nus. 
Hasirs.* The geographical distribution of this race of the 
white-throated wren, so far as known, is confined to the line of 
the United States and Mexican boundary, extending northward 
up the valley of the Colorado, as far as western Nevada, and along 
the Rocky Mountains into Colorado. The corresponding Mexican 
race reaches some distance southward, but has not yet been de- 
tected beyond the limits of Mexico. The habits of both races, 
however, are quite similar, as far as known. 
Dr. Heermann first met with this wren in the spring of 1851, 
on the Cosumnes River. In the following year he procured three 
specimens on the Calaveras River. He describes it as an active, 
sprightly bird, having a loud and pleasing song that may be heard 
a great distance, and which it repeats at short intervals. When 
found, it was occupied with searching for insects, between and 
under the large bowlders of rock that, in some portions of the 
river, are thrown together in confused masses, as if by some ter- 
rific convulsion of nature. 
Dr. Kennerly also met with this species in similar localities 
among the hills bordering upon the Big Sandy, where the 
rocks are also described as piled up thick and high. They 
were darting from rock to rock and creeping among the crevices 
with great activity, constantly repeating their peculiar and sin- 
gular note. The great rapidity of their motions rendered it 
difficult to procure a specimen. He did not observe this bird 
anywhere else. 
a ir occurrence equally in such wild and desolate regions, and 
in the midst of crowded cities, indicates that the abundance of 
their food in either place, and not the absence or presence of man, 
detstinines this choice of residence. When first observed they 
: *By Dr. T. M. Brewer. 
