302 BULLETIN 133, UNITED STATES NATIONAL MUSEUM 



common on the plains that bordered the Rio Negro. Females were 

 prepared as skins on November 23 and 24, and two additional speci- 

 mens, one as a skeleton and one in alcohol, were preserved. 



They ran swiftly along on the ground to pause and stand with 

 head erect, or perched in alert attitudes on fence wires or the tops 

 of bushes. In flight they traveled for long distances barely above 

 the ground to rise finally to a perch on a low bush. Males at inter- 

 vals flew up to make a metallic rattle with their wings as they 

 turned abruptly and dropped to the ground. 



Near Zapala, Neuquen, from December 7 to 9, these flycatchers 

 were observed in little valleys where the grass had been closely 

 cropped by stock. An adult male was taken December 7. Near In- 

 geniero White, the port of Bahia Blanca, Buenos Aires, probably 

 near the northern border of the breeding range, two were recorded 

 on December 13. 



The male in the present species has the two outermost primaries 

 decidedly attenuate, while in the female these two feathers are 

 normal. In addition, the back of the male is more rufescent than in 

 the opposite sex. An adult male, when first taken, had the base of 

 gonys pallid brownish drab; rest of bill, tarsus, and toes black; 

 iris Rood's brown. 



LICHENOPS PERSPICILLATA PERSPICILLATA (Gmelin) 



Motacilla perspicillata Gmelin, Syst. Nat., vol. 1, pt. 2, 1789, p. 969. (Rio 

 de la Plata.) 



Specimens of the widely distributed silverbill were secured at the 

 following localities: San Vicente, Uruguay, January 27, 1921, adult 

 male; Las Palmas, Chaco, July 23, 1920, adult female; Resistencia, 

 Chaco, July 10, adult male; Berazategui, Buenos Aires, June 29; 

 Dolores, Buenos Aires, October 21, adult male and female; Ingeniero 

 White, Buenos Aires, December 13, immature male ; Tunuyan, Men- 

 doza, March 21, 1921, adult male, March 24 and 28, females; General 

 Roca, Rio Negro, November 30, 1920, adult male. Adult males 

 examined from the northern part of the Province of Buenos Aires 

 into Paraguay and southern Brazil have the white patch in the 

 wing at its maximum extent and may be considered as typical of 

 true perspicillata. The black on the outer webs of the primaries 

 extends only 2 or 3 mm. beyond the level of the primary coverts, 

 the median portions of the shafts of the ninth and tenth primaries 

 are white, and the dark distal tip is restricted. The white area 

 forms a prominent streak along the side of the closed wing. The 

 wing varies from 86.2 to 91.5 mm. (average of 12 specimens, 88.8 

 mm.). In skins from near Bahia Blanca, from the valley of the Rio 

 Negi-o, and from Mendoza the white wing patch becomes somewhat 



