68 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



100-105 (101.7); wing, 82-87 (85); tail, 38-1:3 (11.3), forked for 7-11 

 (9.3); exposed ciilmen, 1.5; 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.); Cat. Hirund. Mus. Philad. Acad., 1853, 6. 



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



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

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

 pata, e. Peru). 



Atticora tibialis Baird, Review Am. Biras, ]May, 1865, 307 (Panama E. E. ). — 

 Sclater and Salvin, Proc. Zool. Soc. Lond., 1875, 495 (Colombia). — Ber- 

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

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

 Sharpe, Cat. Birds Brit. Mus., x, 1885, 185, 634 (Panama; Eemedios, province 

 Antioquia, Colombia; Cosnipata, Peru). — Sn^ARPEandWYATT, Mon. Hirund., 

 1894, 501, 517, pi. 97. 



lAtticoral iibialis Gray, Hand-list, i, 1869, 72, no. 859. — Sclater and Salvin, 

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



Genus PYGOCHELIDON Baird. 



. Pygochelidon Baird, Eevievv Am. Birds, May, 1865, 270, 305, 308. (Type, 

 Hirundo cyanoleuca Vieillot. ) 



Small Hirundinida? (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 lit'Ae 

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

 form glossy blue-black, the under parts white with blue-black '^nder 

 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 curv^ed terminally, but 

 tip of maxilla very slightl}^ produced; gonys slightly con v^ex, decidedly 

 ascending terminally, its base forming an obvious an^le; commissure 

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

 roundish, opening latero-superiorlj^, with a narrow superior mem- 

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

 feathering of frontal antiaj. 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 modei-ately contracted termi- 

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

 claw), entirel}^ unfeathered, except at extreme upper end in front, the 

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



« Three specimens, none of thevi with sex determined. 



