56 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



PETROCHELIDON FULVA PALLIDA Nelson. 

 COAHUIIA CLIFF SWALLOW, 



Similar to F. f. fulva (from Cuba), but larger; rump decidedly paler 

 (cinnamon-rufous instead of chestnut or deep cinnamon-rufous); brown 

 central areas of under tail-coverts paler, and the sides and flanks pale 

 grayish brown, more rarely and less strongly tinged or suffused with 

 cinnamon-rufous. 



Young.^ — Similar to the young of I\ f. fulva, but rump paler (vina- 

 ceous-cinnamon instead of cinnamon-rufous), black of pileum and back 

 duller, and sides of head paler. 



Adult male. — Length (skin), 125; wing, 107; tail, 48; exposed culmen, 

 7; width of bill at frontal antia^, 6.6; tarsus, 12; middle toe, 12.* 



Aditlt female.— Length (skins), 125-133 (129); wing, 106.5-110 

 (107.9); tail, 47-49.5(48.6); exposed culmen, 7; width of bill at frontal 

 antia?, 6-6.5 (6.2); tarsus, 12-12.5 (12.1); middle toe, 12-12.5 (12.3).'^ 



Northeastern Mexico, in States of Coahuila (Saltillo, breeding) and 

 Tamaulipas (Miquihuana). 



Petrochelidonfulvapnllida Nelson, Proc. Biol. Soc. Wash., xv, Oct. 10, 1902, 211 

 (Saltillo, Coahuila, n. e. Mexico; coll. U. S. Nat. Mus.). 



Genus STELGIDOPTERYX Baird. 



Stelgidopteryx Baird, Kep. Pacific K. E. Surv., ix, 1858, 312 (Type, Hirundo 

 serripennis Audubon ) . 



Kather small Hirundinidse (wing not more than 120 mm.) with nostrils 

 roundish, opening superiorly; tarsus longer than middle toe without 

 claw; middle toe united to outer toe by at least half its basal pha- 

 lanx; tail nearly even (depth of its emargination less than length of 

 exposed culmen); upper parts plain grayish brown, and outermost 

 primary, in adult male, with the edge roughened by stiff' recurved tips 

 to the barbs. 



Bill much depressed, moderately broad (width at frontal anti^e rather 

 less than length of exposed culmen), the culmen straight to near tip 

 where rather abruptly decurved, forming a slight hook to tip of max- 

 illa; maxillary tomium nearly straight though obviously deflexed 

 basall}^, the subterminal notch small though distinct. Nostrils opening 

 superiorly, roundish, with visible membrane behind it but none above, 

 except posteriorly. Rictal bristles small, scarcely projecting across 

 commissure. Tail about half as long as wing, or less, slightly emar- 



«No. 158851, coll. U. S. Nat. Mus. (Biological Survey collection), female, Miqui- 

 huana, Tamaulipas, June 8, 1898; Nelson and Goldman. 

 ^One specimen. 

 <^Five specimens. 



