686 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



c. Toes naked; tail forked for less than half its length « Tachornis (p. 693). 



cc. Toes feathered; tail forked for more than half its length. 



Claudia (extralimital).^ 

 aa. Toes with the number of phalanges normal (2, 3, 4, 5); hallux more posterior, not 

 reversible, the foot never pamprodactylous nor toes paired; tarsi and toes naked. 

 (Subfamily Chgeturinse .) <^ 

 b. Hallux relatively longer, more than half as long as inner toe. 

 c. Tarsus not longer (usually shorter) than middle toe with claw. 

 d. Size very large (wing not less than 190 mm.); tenth (outermost) primary 

 longest, or at least not distinctly shorter than ninth; distance from tips of 

 longest secondaries to tip of longest primary not more than two-thirds the 

 total length of w4ng; tail two-ninths to one-fourth as long as wing; bill 

 relatively much stouter; under tail-coverts and a flank-stripe white. 



Hirundapus (extralimital).<^ 

 dd. Size smaller (wing less than 170 mm., the wing relatively very long); tenth 

 (outermost) primary distinctly shorter than ninth; distance from tips of 

 longest secondaries to tip of longest primary much more than two-thirds 

 the total length of wing; tail only one-sixth as long as wing, the longest 

 coverts reaching nearly to its tip; no white on under tail-coverts or flanks. 



Mearnsia (extralimital).e 

 cc. Tarsus longer than middle toe with claw. 

 d. Size very large (wing 190-230 mm.); rectrices more firm, with very rigid 

 shafts; adults with a white collar (at least on hindneck). 



Streptoprocne (p. 696). 

 dd. Size much smaller (wing less than 180 mm.); rectrices softer, with less rigid 

 shafts; adults without white collar. 

 e. Tail distinctly emarginate, the rectrices soft, with shafts not at all rigid nor 



produced Nephoecetes (p. 703). 



ee. Tail truncate or slightly rounded or double-rounded, the rectrices firm, 

 with shafts rigid and, sometimes, slightly produced. 



Cypseloides (p. 710). 



bb. Hallux relatively much smaller, not more (usually less) than half as long as 



inner toe Chsetura (p. 714). 



a According to Gosse (Birds of Jamaica, p. 59) the sternum of Tachornis phoenicobia 

 (type of the genus) has two large metasternal foramina and also a foramen perforat- 

 ing the anterior portion of the keel. In this respect Tachornis differs from all other 

 Micropodinse, so far as known, all the latter having both the metasternum and 

 carina sterni entire. 



b Claudia Hartert, Cat. Birds Brit. Mus., xvi, 1892, 469 (type, Cypselus squamatus 

 Cassin. 



The single known species belonging to this genus occurs in Guiana, Brazil, and 

 eastern Peru. 



c =Chseturinse Sclater, Proc. Zool. Soc. Lond., 1865, 597; Stejneger, Stand. Nat. 

 Hist., iv, 1885, 437; Hartert, Das TieiTeich, Piodarg., Caprim., Macropt., 1897, 63, 65. 

 y-Chaeturinae Cams, Handb. Zool., i, 1868-75, 253 (includes Dendrochelidonidae). 



d Hirund-apus Hodgson, Journ. Asiat. Soc. Bengal, v, no. 60, Dec, 1836, 780, in text. 

 (Type, Chsetura nudipes Hodgson.) — Hirundinapus (emendation) Sclater, Proc. Zool. 

 Soc. Lond., 1865 (March, 1866), 607.— Pallene Lesson, Compl. Buffon, viii, 1837, 493. 

 (Type, Cypselus giganteus Temminck.) 



«New genus. Dedicated to Dr. Edgar A. Mearns, U. S. A., not only in recognition 

 of his valuable services to ornithology, but also as a token of the author's high esteem. 

 (Type, Chsetura picina Tweeddale.) 



