The essential features of this family appear to consist in the
combination of the dentirostral bill, notched in both mandibles; the
ten primaries (except _Vireosylvia_), of which the outer is usually
from one fourth to one half the second; the rather short, nearly even
tail, with narrow feathers, and the great amount of adhesion of the
anterior toes,—the whole basal joint of the middle being generally
united on both sides to the adjacent joints, and decidedly shorter
than the basal of inner or two basal of outer. The outer lateral toe
is generally appreciably longer than the inner, reaching considerably
beyond the base of the middle claw. The tarsi are always distinctly
scutellate anteriorly. The young are never spotted, or streaked as in
the Thrushes; nor, indeed, do the adults exhibit such markings.
The _Vireonidæ_ are peculiar to the New World, and are widely
distributed, although but one genus belongs to the United States.