_Nauclerus_, VIG. 1825. (Type, _Falco furcatus_, LINN.; _F.
forficatus_, LINN.)
_Elanoides_, GRAY, 1848. (Same type.)
GEN. CHAR. Form swallow-like, the tail excessively lengthened and
forked, and the wings extremely long. Bill rather small, and narrow;
commissure faintly sinuated; upper outline of the lower mandible very
convex, the depth of the mandible at the base being only about half
that through the middle; gonys drooping terminally, nearly straight.
Side of the head densely feathered close up to the eyelids. Nostril
ovoid, obliquely vertical. Feet small, but robust; tarsus about equal
to middle toe, covered with large, very irregular scales; toes with
transverse scutellæ to their base; claws short, but strongly curved;
grooved beneath, their edges sharp. Second or third quill longest; first
shorter than, equal to, or longer than, the fourth; two outer primaries
with inner webs sinuated. Tail with the outer pair of feathers more than
twice as long as the middle pair.
The genus contains but a single species, the N. FORFICATUS, which is
peculiarly American, belonging to the tropical and subtropical portions
on both sides of the equator. The species is noted for the elegance of
its form and the beauty of its plumage, as well as for the unsurpassed
easy gracefulness of its flight. It has no near relatives in the Old
World, though the widely distributed genus _Milvus_ represents it in
some respects, while the singular genus _Chelictinia_, of Africa,
resembles it more closely, but is much more intimately related to
_Ictinia_ and _Elanus_.
[Illustration:
=52994=, ♂. ½
=52994=, ♂. ½
=52994=, ♂. ¼ ¼
_Nauclerus forficatus._]
Species.
=N. forficatus.= Head, neck, entire lower surface, and band across
the rump, immaculate snowy-white; upper surface plain polished
blackish, with varying lights of dark purplish-bronze (on the back
and shoulders) and bluish-slaty, with a green reflection in some
lights. _Young_, with dusky shaft-streaks on the head and neck,
and the feathers of the upper parts margined with white. Wing,
15.40–17.70; tail, 12.50–14.50; culmen, .70–.80; tarsus, 1.00–1.30;
middle toe, 1.15–1.20. _Hab._ The whole of tropical, subtropical, and
warm-temperate America. Accidental in England.
Nauclerus forficatus, (LINN.) RIDGWAY.