BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 261 



regions cited in the original reference. These are the city of Goyaz, 

 Engenho do Cap Gama, and Cuyaba. 



The limited series in the United States National Museum does not 

 permit the description of new forms among the birds placed under 

 this name, although one or more are probably represented. It may 

 be noted that specimens that I secured at Rio Negro, Uruguay (in 

 worn plumage), are slightly darker above than skins from the Chaco, 

 while examples from the Chaco in turn seem slightly darker than 

 those from Brazil. 



This form was recorded and secured as follows: Resistencia, 

 Chaco, July 9, 1920 (adult male secured) ; Las Palmas, Chaco, July 

 19 to 30 (female, July 19, and male, July 30) ; Riacho Pilaga, For- 

 mosa, August 7 to 21 (males, August 7 and 9) ; Kilometer 80, west 

 of Puerto Pinasco, Paraguay, September 15 (adult male) ; Rio 

 Negro, Uruguay, February 14 to 19 (male and female immature, 

 February 14, adult male, February 17, and immature male, February 

 18) ; Tapia, Tucuman, April 9 (immature female) and 11 (adult 

 male). This form is recorded by Hellma3^r from Buenos Aires west 

 to Cordoba, Tucuman, and Salta, and north probably to the plains 

 of Bolivia. Tremoleras has noted it from Montevideo and Canelones 

 in Uruguay. 



Synallaxis f. frontalis has chosen as its haunt dense growths of 

 weeds or thorny plants and heavy thickets, usually in low areas 

 shaded by groves. It was especially common in the Chaco and in 

 the dense thickets along the Rio Negro, in western Uruguay, and 

 elsewhere was found in smaller numbers. The birds were found 

 throughout the winter in bands containing from three to eight, ap- 

 parently family parties still in company from the previous season, 

 that often fed in growths of heavy grass at the borders of thickets. 

 When startled they flew a short distance with tilting flight to some 

 secure cover and at times paused in the open for a few seconds 

 before disappearing among the branches. Frequently they fed 

 among the leaves of bushes or dense herbage, usually near the 

 ground, where they were constantly in motion. When not hopping 

 about restlessly they peer quickly from side to side, at the twigs 

 below or the leaves above, flitting the wings and twitching the long 

 tail. All of these activities were carried on behind a screen of 

 leaves so that only occasionally did a glimpse of them offer through 

 some little opening. 



They appear much richer in color in life than in the form of a 

 skin, as the dark browns and grays of their plumage enlivened by 

 touches of rufous on crown, wings, and tail form a pleasing combi- 

 nation. The feathers of the throat in life are puffed out so that their 

 slaty black bases form a shield-shaped patch that appears almost 

 black. 



54207—26 18 



