_Tachycineta_, CAB. Mus. Hein. 1850, 1851, 48. (Type, _H. thalassina_,
SW.)
[Line drawing: _Hirundo thalassina._
1895]
GEN. CHAR. Nostrils lateral, overhung or bordered internally by
incumbent membrane. Tarsi with the tibial joint covered by overhanging
feathers, adherent a short distance along inner face, about equal to
middle toe without claw. Lateral toes equal. Adhesion of basal joint
of middle toe variable. Tail emarginate only, or slightly forked; fork
not exceeding half an inch in depth. Color blue or green above, with
or without metallic gloss; with or without white rump. Entirely white
beneath. Nest usually in holes of trees or rocks; eggs pure white,
unspotted.
Of this section there are two North American species, differing as
follows, both being green above and white beneath:—
Species.
Plumage above soft and velvety without metallic gloss. Sides of
head, space around eyes, and whole under parts, white; with the
feathers all plumbeous at base. Female duller in plumage. Young
with bases of throat-feathers gray to roots.
T. thalassina. Above velvety-green, with various shades and
tinges of violet and purple.
Plumage above compact, and with rich green metallic gloss. Sides
of head to line with eyes like its upper part. Beneath white; the
feathers of chin and throat, and generally of crissum, white to
base. A concealed spot in jugulum. Female duller. Young with
bases of throat-feathers pure white to roots.
T. bicolor. Above metallic-green. Inside of wings and
axillars ash-color.
Hirundo bicolor, VIEILL.