1Y2 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



KEY TO THE SPECIES OF XENOPS.o 



a. Breast plain brown, brownish gray, or grayish olive. {Xenops genibarbis.) 



b. Basal portion of rectrices more extensively black. (Tropical South America.) 



Xenops genibarbis genibarbis (extralimital).& 

 bb. Basal portion of rectrices less extensively black. (Southern Mexico to Panama.) 



Xenops genibarbis mexicanus c (p. 172.) 

 aa. Breast conspicuously streaked with whitish. (Xenops rutilus.) 



b. Under parts more broadly streaked; back, etc., brighter rufous-brown. (Brazil, 



etc Xenops rutilus rutilus (extralimital).<^ 



66. Under parts more narrowly streaked; back, etc., duller rufous-brown. (Costa 

 Rica to Colombia, Venezuela, Trinidad, and Peru.) 



Xenops rutilus heterurus (p. 175). 



XENOPS GENIBARBIS MEXICANUS (Sclater). 



MEXICAN XENOPS. 



Similar to X. g. geniharhis « but with much less of black on basal 

 portion of lateral rectrices. 



Adults (sexes alike). — Pileum brown (nearly bister), the feathers 

 sometimes witli very indistinct shaft-streaks of paler (these usually 



o Both species of Xenops almost certainly require further subdivision than is here 

 made, but from want of sufficient material, especially of X. rutilus and South American 

 representatives of X. genibarbis, I must leave a satisfactory treatment of the genus 

 to some one who has both more material and time. (See, however, Hellmayr, in 

 Novit. Zool., xiv, 1907, 54, 55, whose paper I did not, unfortunately, see in time 

 to utilize it in this work.) 



b Xenops genibarbis Illiger, Prodromus Orn., 1811, 213 (Cameta, Brazil); Sclater, 

 Cat. Birds Brit. Mus., xv, 1890, llO.—Neops ruficaudus Vieillot, Analyse, 1816, 68 

 (Guiana). — (?)Xcnops UUoralis Sclater, Proc. Zool. Soc. Lond., 1861, 379 (Esmeral- 

 das, w. Ecuador; coll. P. L. Sclater). — (l)Xenops approximaus Pelzeln, Sitz. Akad. 

 Wien, xxxiv, 1859, 113. 



In the paper referred to above Hellmayr (than whom there is no better authority), 

 divides X. genibarbis into three subspecies (besides X. g. mexicanus), as follows: 

 (1) Xenops genibarbis genibarbis (Colombia to Cayenne and Amazon Valley); (2) 

 Xenops genibarbis littoralis (western Ecuador); (3) Xenops genibarbis pelzelni (south- 

 eastern Brazil, from Bahia to S. Paulo; new subspecies, described on p. 55, the type, 

 in coll. Vienna Mus., being from Ypanema, S. Paulo). 



c This probably separable into about three subspecies. (See p. 174, footnote.) 



d X[enops] rutilus Lichtenstein, Verz. Doubl., 1823, 17 (Bahia, Brazil; coll. Berlin 

 Mus.); Sclater, Cat. Birds Brit. Mus., xv, 1890, 111, part. — Xenops rutilus rutilus 

 Hellmayr, Novit. Zool., xiii, 1906, 29 (Trinidad; crit.); xv, 1908, 62 (Goiaz, etc., 

 Brazil; crit.). — Xenops rutilans Temminck, PI. Col., livr., 12, July, 1821, pi. 72, 

 fig. 2. — Xenops affinis Swainson, Anim. in Menag., pt. iii, Jan. 1, 1838, 352 (Brazil; 

 coll. W. Swainson). — Xenops argyobronchus Bertoni, Aves Nuevas del Paraguay, 

 Jan , 1901, 75 (DjaguarasapA, lat. 26° 53', upper Rio Parana, Paraguay; coll. A. de W. 

 Bertoni; see Arribdlzaga, An. Mus. Nac. Buenos Aires, vii, 1902, 352, 358 and Iher- 

 ing. Rev. Musi. Paulista, vi, 1904, 328). 



< See p. 172. 



