Birds of America
By John James Audubon, F. R. SS. L. & E.
FAMILY XX.--VIREONINAE. GREENLETS.
Bill of moderate length, straight, rather stout, compressed toward the end;
gap-line slightly arched, notches distinct, tip very small, declinate. Head
rather large, ovate; neck short; body rather slender. Feet of moderate length;
tarsus compressed, slender, with seven anterior scutella; toes rather small,
hind toe rather stout, lateral equal. Claws moderate, arched, compressed,
acute. Plumage soft and blended. Wings of moderate length, rather pointed.
Tail of moderate length, even or emarginate. Roof of upper mandible concave,
with a median ridge; tongue narrow, flat above, with the point slit; oesophagus
of moderate length, without dilatation; stomach roundish, muscular, with a dense
rugous epithelium; intestine short, and rather wide; coeca very small. Trachea
simple, with four pairs of inferior laryngeal muscles.