BIBDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 303 



more restricted, so that instead of seven outer primaries that are 

 nearly white the number is reduced to six, as the outer web of the 

 fourth primary is extensively black. The black on the others is 

 also increased both on the outer web and at the tip. The wing varies 

 from 92 to 93.6 mm. (average of three specimens, 92.7 mm.). These 

 show a distinct approach to andina, but are nearer perspiciUata. 

 Finally, at Zapala and from the region south of the Rio Negro come 

 specimens in which the black on the outer webs of the primaries 

 may extend 5 or 6 mm. beyond the primary coverts, in which the 

 shafts are black and the distal dark patch extensive. The wing in 

 these ranges from 90.1 to 96.2 mm. (average of four specimens, 

 92.9 mm.). Though the white may be somewhat more extensive 

 than in some from Chile, these seem best referred to andina. In 

 these the white in the closed wing appeared streaked with black 

 owing to the extent of the dark markings on the outer webs of the 

 primaries. 



A male taken at San Vicente, Uruguay, January 27, is molting 

 the body feathers, while in three from Timuyan, Mendoza (March 

 21 to 28), the outer primaries are being renewed. 



Following are the localities and dates when this flycatcher was 

 recorded : Berazategui, Buenos Aires, June 29, 1920 ; Resistencia, 

 Chaco, July 9 and 10; Las Palmas, Chaco, July 13 to August 1; 

 Riacho Pilaga, Formosa, August 8 to 20 ; Formosa, Formosa, August 

 23; Puerto Pinasco, Paraguay, September 3; Kilometer 80, west of 

 Puerto Pinasco, September 17; Dolores, Buenos Aires, October 21; 

 Lavalle, Buenos Aires, October 23 to November 15; General Roca, 

 Rio Negro, November 23 to December 3; Ingeniero White, Buenos 

 Aires, December 13; Carrasco, Uruguay, January 9 and 16, 1921; 

 La Paloma, Rocha, January 23; San Vicente, Rocha, January 27 to 

 February 2 ; Lazcano, Rocha, February 5 to 9 ; Potrerillos, Mendoza, 

 March 16 ; Tunuyan, Mendoza, March 22 to 29. 



The silverbill is restricted in its haunts to the vicinity of water. 

 Though common in the Chaco north to the Rio Pilcomayo, it seemed 

 rare or local beyond. In the pampas it was locally common in 

 northern Buenos Aires, but was not detected in the regions that I 

 visited near Guamini or Carhue. In northern Rio Negro it frequented 

 the vicinity of streams, but was also common in the irrigated alfalfa 

 fields, haunts that will enable the bird to extend its range, as culti- 

 vation, through enlarged irrigation projects, increases in the arid 

 sections of northern Patagonia and western Argentina. In the 

 Province of Mendoza, where part of the birds noted may have been 

 migrant from the south, the species was found along streams and 

 irrigating ditches, on one occasion at an altitude of 1,500 meters in 

 the vallev at Potrerillos. 



