30 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



dd. Feathers of lower abdomen with a concealed very broad bar or band of 

 white; tail relatively longer and more deeply forked, with lateral rec- 

 trices relatively narrower and more pointed. (Cuba; accidental or occa- 

 sional in southern Florida. ) Progne cryptolenca, adult male (p. 37) 



cc. No concealed white patch on outer margin of sides; tail forked for more 

 than 25 mm. (Chile, Argentina, and Paraguay.) 



Progne furcata, adult male (extralimital«) 

 bh. Wing not more than 130 mm. (usually much less) ; no concealed white patch 

 on sides of lower back. (Galapagos Archipelago. ) 



Prague modesta, adult male (p. 43) 

 aa. Under parts not entirely steel blue. 

 h. Under parts dark steel blue anteriorly and laterally, the abdomen and under 

 tail-coverts pure white, 

 c. Larger (adult male averaging wing 143.5, tail 74.2, exposed culmen 11.2, width 

 of bill at frontal antise 9.4, tarsus 14.1, middle toe 15). (Jamaica, Porto 

 Rico, and Haiti; Lesser Antilles.) 



Progne domiuicensis, adult male (p. 38) 



rr. Smaller (adult male averaging wing 136.7, tail 69.5, exposed culmen 10.1, 



width of bill at frontal antise, 8.4; tarsus, 13.2; middle toe, 14). (Western 



Mexico.) A Progne sinaloae, adult male (p. 40) 



66. Under parts without any steel blue, or else with the chin and throat sooty 

 gray. 

 I. Under parts partly white (at least the abdomen white or mixed with whitish 

 and much paler than chest. 

 d. A more or less distinct hoary space on sides of neck, often united across 

 hindneck and forming a more or less distinct collar. {Progne subU, 

 adult female and young. ) 

 e. Darker, the under parts sometimes without any white except on lower 

 abdomen and margins of under tail-coverts; forehead less distinctly 

 and less extensively hoary, sometimes glossy blue-black, like rest of 

 upper parts. --Progne subis subia, adult female and young (pp. 31, 32) 

 ee. Paler, the under parts always extensively white, the forehead more dis- 

 tinctly and extensively hoary. 



Progne subis hesperia, adult female and young (p. 35) 

 dd. No hoary space on sides of neck, which are dark sooty gray; no trace of 

 collar across hindneck. 

 e. Larger (averaging wing 140, tail 68 or more, tarsus 14.4 or more), with 

 tail more deeply forked (depth of fork averaging 17.5 or more); sooty 

 gray of chest and sides deeper and more uniform, more strongly con- 

 trasted with white of abdomen. v 



Progne cryptolenca, adult female and young (p. 37) » 



Progne dominieensis, adult female and young (p. 38) * 



ee. Smaller (averaging wing 133.3, tail 64.1, tarsus 13.6) , with tail less deeply 



forked (depth of fork averaging 12.7 «); sooty gray of chest and sides 



aProgne furcata Baird, Eeview Am. Birds, May, 1865, 278 (Chile; coll. U. S. Nat. 

 Mus.); Sharpe, Cat. Birds Brit. Mus., x, 1885, 175; Sharpe an*Wyatt, Mon. Hlrund., 

 1894, 459, 487, pi. 89.— Pro(/«e elegans Baird, Review Am. Birds, May, 1865, 275, part 

 (except adult male only, which = P. mhis mbis; Vermejo R., Paraguay; coll. U. S. 

 Nat. Mus.). 



61 am unable to give characters for distinguishing females and young of these two 

 species. 



<^ These average measurements arc of the adult female only; immature males, which 

 are not different in plumage from adult females, average larger. The measurements 



