GEOTHLYPIS. 221 
Total length, 4.40; wing, 2.15; tail, 2.30; graduation, .25 ; width of outer 
tai] feather, .28; difference between Ist and 3d quills, .15 ; length of bill from 
forehead, .52, from nostril, .30; along gape, .60; tarsus, .75; middle toe and 
claw, .66; claw alone, .18; hind toe and claw, .48; claw alone, .26. 
In autumnal plumage the whitish of the belly becomes tinged with 
yellowish, affording but little distinction from the yellow of the 
breast and crissum. The black becomes obscured, especially that 
on top of the head, by the extension forward of the brownish of the 
vertex. The eyelids are apt to show a whitish ring. There appears 
to be a tendency in the bill to become lighter colored, especially the 
lower mandible, as in Jcteria. I have not yet seen an autumnal 
male with the black bill so characteristic of spring specimens. 
Specimens vary in the width of the black forehead, in that of the 
hoary gray behind it; the whole crown being sometimes of the latter 
color, and the occiput behind it. 
In some western specimens the size is a little larger, and the bill 
appears considerably stouter than in the eastern, but I cannot see 
any other difference. : 
West Indian, Mexican, and Guatemalan specimens do not present 
appreciable differences, except what arises from their autumnal 
dress ; all have the paler bills referred to above. 
The female bird either lacks the black mask entirely, or else it is 
only appreciable on the sides of the head; the whole top of the 
head is usually strongly tinged with reddish-olive. The feathers on 
the eyelids are generally whitish.in the female and autumnal male, 
quite different from the pure black of the spring male. 
I find considerable difference in‘specimens of this species, both as 
to size and extent to which the yellow of the breast reaches over the 
abdomen, ete. In some the black frontal band is bordered behind 
by a narrow band of gray, abruptly defined against the olive of the 
crown (2,535); in others it is of greater extent, and shades more 
insensibly into the olive. In 10,957, from Fort Bridger, and some 
others, this gray is nearly white, and as broad as or broader than the 
black. I am, however, unable to see any permanent characters 
looking to a separation into two species. The characters assigned 
by Swainson for his 7richas brachydactylus, as distinguished from 
T. personatus, appear to be common to all specimens of Maryland 
Yellowthroat I have ever seen. 
All specimens from Washington appear smaller, with slenderer 
bills than others. 
As this species is found distributed throughout the entire extent 
of the United States, from the Atlantic to the Pacific coast, and up 
