BIRBS OF NORTH AND MIDDLE AMERICA. 67 



Genus NEOCHELIDON Sclater. 



Neochelidon Sclater, Cat. Am. Birds, 1862, p. xvi. (Type, Petrockelidon tibialis 



Cassin. ) 

 Microchelidon (not of Beiehenbach, 1853) Sclater, Cat. Am. Birds, 1862, 39. 



(Type, Peiroehelidon tibialU Cassin. ) 



Very small Hirundinidse (wing about 87 mm.) with the small, 

 roundish nostrils opening superiorly ; tarsus longer than middle toe 

 (without claw); middle toe united to outer by whole of its basal and 

 nearly all of its subbasal phalanx, and to inner toe by all or nearly 

 all of its basal phalanx; tail shorter than distance from bend of wing 

 to tip of longest secondaries, forked for about one-fourth its length; 

 tibial feathers much developed, entirely concealing tibio-tarsal joint; 

 coloration sooty black above, sooty brown beneath, the tibial plumes 

 white. 



Bill very small (length from nostril only about half distance from 

 nostril to eye); exposed culmen about equal to basal width of bill, 

 about half as long as tarsus, decidedly curved from base; gonys slightly 

 convex, without distinct basal angle; maxillary tomium nearly 

 straight, the subterminal notch distinct. Nostrils small, roundish or 

 ovate, opening superiorly, with little of membrane visible below 

 (scarcely any above) posterior portion. Rictal bristles minute, nearly 

 obsolete. Tail about half as long as wing, forked for about one-fourth 

 its length, the width of lateral rectrices not decreasing till near the 

 end, where rather abruptly contracted, the tips obtuselj' pointed. 

 Tarsus longer than middle toe (without claw), the upper portion 

 hidden by the unusually developed tibial feathers; middle toe united 

 to outer by the whole of its basal and nearly all of its subbasal pha- 

 lanx, vo the inner toe by all, or nearly all, its basal phalanx; claws of 

 lateral iocs scarcely reaching to base of middle claw. 



Coloration. — Sooty blackish above, paler sooty on rump; under parts 

 plain sootj brown, the thighs white. 



NidAfication. — Nest in hole in bank, composed of fine grasses, etc.; 

 eggs unknown. 



Range. — IstLmus of Panama to Peru. (Monotypic.) 



The single known species of this genus bears a remarkably close 

 resemblance in coloration and general appearance to some of the 

 smaller species of Ohaetura. 



ISIEOCHELIDON TIBIALIS (Cassin). 

 ■WHITE-THIGHED SWALLOW. 



Adults {sexes alike). — Above sooty black, becoming sooty gra,yish 

 brown on rump, the wmgs t'.nd tail hardly so dark as back and pileum; 

 beneath plain sooty grayish brown, the tibial feathers white, in con- 

 spicuous contrast; bill, legs, and feet brownish black; length (skins), 



