BIRDS OF NORTH AND MIDDLE AMERK'A. 67 



Genus NEOCHELIDON Sclater. 



Neochelidon Sclater, ("at. Am. Birds, 1862, p. xvi. (Type, Petrochelidon tibialis 



Cassin. ) 

 MicrocheUdon (not of Keiclu-ubach, 1853) Sclater, Cat. Am. Birds, 1862, 39. 



(Type, Fetroche/lddii tibialix Cassin.) 



Very sniiill liiraiulinidsy (wiug- about 87 mm.) with the simill, 

 roundish nostrils opiMiino" superiorl}' ; tarsus h^ig-er than middk- toe 

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

 nearh" all of its sub})asal ])halanx, and to inner toe by all or nearly 

 all of its basal phalanx; tail shorter than distance from ])end of wing 

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

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

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

 white. 



Bill very small (length from nostril only al)Out 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; gon3's slightly 

 convex, without distinct basal angle; maxillarv tomium nearly 

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

 ovate, opening superiorly, with little of membrane visible below 

 (scarcel}^ an}^ above) posterior portion. Rictal ])i-istles 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 aljruptly contracted, the tips obtusely pointed. 

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

 hid len b}" the unusually developed tibial feathers; middle toe united 

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

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

 lateral toes scarcely reaching to base of middle claw. 



( '(>loratlo)i. — Sooty blackish above, paler sooty on rump; under i)arts 

 plain soot\ brown, the thighs white. 



Nidifi cation. — Nest in hole in bank, composed of line grasses, etc.; 

 eggs unknowLv 



R<in<ji\ — Isthmus of Panama to Peru. (Monotvpic.) 



The single known species of this geiuis bears a remarkably close 

 resiMublance in cidoration and general appearance to some of the 

 smaller species of L 'Ii;vtur<i. 



NECCHELIDON TIBIALIS ( Cassin) . 

 WHITE-THIGHED SWALLOW. 



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

 brown on rump, the wings vv\& tail hardly so dark as back and ])il(Hun; 

 beneath plain sooty graj'ish brown, the tibial feathers white, in con- 

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



