68 BULLETIN 50, UNITED STATES NATIONAL MCTSEUM. 



100-105 (101.7); wing, 8^87 (85); tail, 38-43 (41.3), forked for 7-11 

 (9.3); exposed culmen, 4.5; tarsus, 9-9.5 (9.2); middle toe, 7-8 (7.7).« 

 Isthmus of Panama and southward to western Ecuador (Chimbo) and 

 Peru (Cosnipata). 



Petrochelidon ? tibialis Cassin, Proc. Ac. Nat. Sci. Philad., vi, 1853, 370 ("Brazil;" 



coll. Ac. Nat. Sci. Philad.); Oat. Hirund. Mtis. Philad. Acad., 1853, 6. 

 Microchelidon tibialis Sclatek, Cat. Am. Birds, 1862, 39 ("Brazil"). 

 Neochelidon tibialis Sclatee, Cat. Am. Birds, 1862, p. xvi, errata. — Sclatek and 

 Salvin, Proc. Zool. Sec. Lond., 1864, 347 (Panama R.R.); 1869, 597 (Cosni- 

 pata, e. Peru). 

 AUicora tibialis Baikd, Review Am. Biras, May, 1865, 307 (Panama R. R.).— 

 Sclatek and Salvin, Proc. Zool. Soc. Lond., 1875, 495 (Colombia). — Bbk- 

 LEPSCH and Taczanowski, Proc. Zool Soc. Lond., 1883, 543 (Chimbo, w. 

 Ecuador). — Salvin and Godman, Biol. Centr.-Am., Aves, i, 1883, 231. — 

 Shahpe, Cat. Birds Brit. Mus., x, 1885, 185, 634 (Panama; Remedies, province 

 Antioquia, Colombia; Cosnipata, Peru). — Shakpe and Wyatt, Mon. Hinmd., 

 1894, 501, 517, pi. 97. 

 {Atticora'] tibialis Gkay, Hand-list, i, 1869, 72, no. 859. — Sclatek and Salvin, 

 Nom. Av. Neotr., 1873, 14 (Peru; Panama). 



Genus PYGOCHELIDON Baird. 



Pygochelidon Baikd, Review Am. Birds, May, 1865, 270, 305, 308; (Type, 

 Hirundo cyanoleuca Vieillot. ) 



Small Hirundinidse (wing about 100 mm.) with very short and 

 relatively deep bill, the small, roundish nostrils opening superiorly; 

 tarsus longer than middle toe (without claw), entirely unfeathered 

 except extreme upper end in front; middle toe united to outer by 

 whole of basal phalanx; tail about half as long as wing (or a little 

 more), forked for less than one-fourth its length; upper parts uni- 

 form glossy blue-black, the under parts white with blue-black under 

 tail-coverts. 



Bill very short (exposed culmen less than half as long as distance 

 from nostril to eye), but relatively deep and narrow, its depth at 

 base of exposed culmen nearly equal to its width at same point; cul- 

 men nearly straight basally, more decidedly curved terminally, but 

 tip of maxilla very slightly produ'ced; gonys slightly convex, decidedly 

 ascending terminally, its base forming an obvious angle; commissure 

 straight, its subterminal notch minute but distinct. Nostril small, 

 roundish, opening latero-superiorty, with a narrow superior mem- 

 braneous operculum, posteriorly in contact, or very nearly so, with 

 feathering of frontal antise. Rictal bristles obvious, but small. Tail 

 about half as long as wing (or a little "more), forked for less than one- 

 fourth its length, the lateral rectrices moderately contracted termi- 

 nally and obtusely pointed. Tarsus longer than middle toe (without 

 claw), entirely unfeathered, except at extreme upper end in front, the 

 tibial feathers short; middle toe united to outer toe by whole of its 



o Three specimens, none of them with sex determined. 



