204 U. S. P. R. R. EXP. AND SURVEYS-ZOOLOGY—GENERAL REPORT. 
In preparing the following diagnoses and descriptions of the families, sub-families, and genera 
of American Oscines, I have, as already stated, been mainly obliged to make up the characters 
for myself by personal examination of the species. Without the time or the immediate oppor¬ 
tunity to extend this criticism to the exotic forms, I have not succeeded as well as I could have 
wished, but it cannot be long before some one will take up the subject on the new basis, and 
work out the details into an acceptable system. The work of Burmeister on the birds of Brazil, 
containing many original and important remarks on the subject, did not reach me until too late 
a period to make the use of it I could have wished, although I have derived many valuable hints 
from it. 
The following synopsis may serve to facilitate the determination of the families, and a conse¬ 
quent reference to the page where they are described in rather more detail. 
A. Primaries, nine. Outer primary nearly as long as, or more than half, the next. Legs 
scutellate anteriorly. 
a. Commissure straight. 
Hirundinidae. —Bill very broad, short, and much depressed ; the culmen less than 
half the commissure, which opens to beneath the eye. Rictus smooth. Wings 
very long, greatly exceeding the tail; the first primary longest. Tarsi shorter 
than the lateral toes. 
Sylvicolidae. —Bill usually slender, conical, elongated, and acute ; or, if broad 
and depressed, the culmen more than half the gape or commissure, and the rictus 
with bristles. Tarsus always longer than the lateral toes. Wings rather short, 
never much longer than the tail. First primary generally shorter than second. 
b. Commissure angulated at base. 
Fringillidae. —Bill much shorter than the head ; thick, conical, the tip usually 
notched, and the rictus with bristles. 
Icteridae. —Bill nearly as long as, or longer than, the head, without notch or 
bristles. 
B. Primaries, ten. First primary very short, (spurious,) the second nearly as long as the 
third. Bill, with the culmen gently curved, and the upper mandible notched at tip. 
a. Lateral toes about equal. Basal joint of middle toe mostly free internally. 
Turdidae. —Tarsi encased in one heavy “boot,” without scutellae ; posterior 
edge acute ; hind claw curved. 
Alaudidae. —Tarsi blunt behind ; scutellate anteriorly and posteriorly, but not 
laterally. Spurious primary sometimes wanting. Hind claw long, nearly 
straight. 
b. Outer lateral toe much longest. Basal joint of middle united throughout. 
Certhiadae. —Legs scutellate anteriorly. Hind toe very long. Claw curved. 
C. Primaries, ten. The first spurious, sometimes wanting, or less than half the second. Bill, 
with both mandibles, abruptly hooked, and conspicuously notched at the tip, with a tooth behind 
the notch above. 
Bombycillidae.— Bill broad, depressed, weak, moderately hooked. Tarsi shorter 
than middle toe. 
Laniidae. —Bill narrow, much compressed, and very powerful, strongly hooked. 
Tarsus longer than middle toe. 
