BIKDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 271 



ground where it was difficult to reach it. This nest was composed of 

 firmly interlaced thorny twigs that made a ball 200 mm. in diameter. 

 At one side near the top was an entrance opening, located among 

 thorny limbs of the shrub, and further protected by small spiny 

 twigs grouped about it. After some difficulty I opened the stinicture 

 to find that the interior cavity was firmly and closely felted with a 

 lining of fur from the introduced hare, a device that not only made 

 B, safe cushion for the eggs and young, but also gave protection 

 from the severe winds of this region, that otherwise had free pas- 

 sage amid interstices in the nest material. This nest contained two 

 white eggs, that when first seen were beautifully tinted by the yolk 

 within through the somewhat translucent shell. When blown they 

 became dull white in color. These eggs measure as follows, in milli- 

 meters: 18.4 by 14.4, and 18 by 14.6. In form the eggs are rather 

 bluntly pointed with little distinction between large and small ends. 

 It is probable that tAvo broods are reared in a season, as young only 

 recently grown were taken in March. 



SIPTORNIS PATAGOKICA (d'Orbigny) 



Synallaxis patagonica d'ORBiGNY, Yoy. Amer. Merid., Ois., 1835-1844, p. 

 249. (Banks of the Rio Negro.) 



Near General Koca, Rio Negro, from November 23 to December 2, 

 1920, the present species was fairly common ; adult females were col- 

 lected on November 23 and 24 and a male on November 25. The 

 skins preserved do not differ appreciably from two taken near San 

 Antonio del Oeste, not far from the type locality. The species has 

 been recorded west to the Rio Limay in Neuquen,*° a short distance 

 beyond Roca. The throat in patagonica of both sexes has the 

 feathers slate at the base with the tips white, forming a distinct dark 

 throat patch spotted rather irregularly with white, as prominent as 

 the throat patch of Synallaxis f. frontalis. No mention of this is 

 made in the description in the British Museum Catalog (vol. 15, 

 p. 69), and in the key (p. 65) the throat is said to be unspotted, 

 though the original description by d'Orbigny describes the throat 

 as distinctly marked. The species differs notably in structural char- 

 acters from the stiff-tailed forms of Siptornis and in some ways 

 seems quite aberrant. 



This bird was found in the semiarid region that bordered the Rio 

 Negro, where it frequented the denser, taller stands of Atriplex and 

 other shrubs that grew in the river bottom or occurred more spar- 

 ingly in the smaller, more scattered growth that clothed the gravel 

 hills above the flood plain. Individuals hopped about among the 

 twigs or walked slowly around on the ground, always under protec- 



"Hellmayr, Nov. ZooL, vol. 28, September, 1921, p. 268. 



