Birds of America
By John James Audubon, F. R. SS. L. & E.
GENUS VI.--PHAETON, Linn. TROPIC BIRD.
Bill as long as the head, stout, very much compressed, slightly curved,
tapering, acute, opening to beneath the eye; upper mandible with the dorsal line
slightly arched, the ridge narrow, rounded, the sides sloping and slightly
convex at the base, nearly erect towards the end, the edges sharp, direct,
irregularly broken, the tip acuminate; nasal groove short, near the ridge; lower
mandible with the angle long, and extremely narrow, the dorsal line straight and
ascending, the sides erect and slightly convex, the tip acuminate. Nostrils
basal, linear, very small. Head rather large, ovate; neck short and thick; body
rather full. Feet very short; tibia bare for a considerable space; tarsus
extremely short, roundish, covered with small round scales; toes rather small,
placed in the same plane, and connected by reticulated webs; first very small,
third a little longer than fourth, all scutellate above. Claws small, arched,
compressed, rather sharp, that of the third toe with a thin entire inner edge.
Plumage soft, blended, on the back rather compact. Wings long, acute, the first
quill longest. Tail of twelve feathers, tapering, the two middle feathers
extremely elongated, narrow, and tapering. This genus appears to be
intermediate between Sula and Sterna.