BIKDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 313 

 ENTOTRICCUS STRIATICEPS (d'Orbigny and Lafresnaye) 



Muscisaxicola striaticeps d'ORBiGNrr and Lafbesnaye, Mag. Zool., 1837, 

 cl. 2, p. 66. (Chiquitos, Bolivia.) 



Dr. Hellmayr ^° has determined that this species, known for many 

 years as einer^eus Sclater,^^ should bear the name of striaticeps as in- 

 dicated above. He writes that the type, in the Paris Museum, is 

 labeled as taken at Chiquitos, Bolivia, though in the original descrip- 

 tion the species is said to come from La Paz. The greatly narrowed 

 l)rimaries in this species distinguish it not only from Knipolegus, 

 but also from all other flycatchers. Mr. Ridgway described the pequ- 

 liarities of this bird when he erected the genus Phaeotriccus, but as 

 through inadvertence he designated Gnipolegus hudsoni as type, the 

 name PTiaeotnccus must be used for hudsoni. As striaticeps is un- 

 doubtedly peculiar, the present writer and Peters"^ have proposed 

 that it be called Entotriccus. It is characterized by greatly nar- 

 rowed primaries with the sixth to the tenth (outermost) distinctly 

 falcate; seventh primary longest; tenth shorter than the first. 



This flycatcher was recorded at the following points: Riacho 

 Pilaga, Formosa, August 8 (adult female taken), 13 (two females 

 and a male) and 18; Puerto Pinasco, Paraguay, September 3; Kil- 

 ometer 80, west of Puerto Pinasco, September 9, 10 (a female shot) 

 and 15 ; Tapia, Tucuman, April 7 to 13, 1921 (two males and a female 

 taken April T and 9). The female taken at Tapia is less heavily 

 streaked on throat and breast than skins from the Chaco, so that it 

 is paler below, a difference due in part perhaps to the fact that the 

 specimen is in fresh fall plumage. Females are identical with 

 males in wing formula and in the narrowed form of the primaries. 



In the Chaco, during the winter season, these alert little flycatchers 

 sought low perches on the sheltered sides of dense groves of forest, 

 where they were protected from cold winds. In the warmer, more 

 open scrub near Tapia, Tucuman, they were scattered at random 

 through little valleys, though more frequent perhaps along deep- 

 cut barrancas that were common in this region. When at rest the 

 tail twitched constantly, heightening their superficial resemblance 

 to smaU Empidonax. During warm forenoons, in pleasant weather, 

 males, from a perch at the top of a low tree or a dead limb, frequently 

 shot straight up for a distance of 20 feet, turned and descended head 

 first, with closed wings until just above the former perch, when the 

 velocity of their fall was checked with a sudden rattle of wings, and 

 the bird once more was at rest, as nonchalant and jaunty as though 



s«Nov. Zool., Julj', 1906, pp. 318-319. 



"^ Cnipolef/us cinereus Sclater, Proc. Zool. Soc. London, 1870, p. 58. (Corumba, 

 Matto Grosso.) 



"» Proc. Biol. Soc. Washington, vol. 36, May 1, 1923, p. 144. Type, by original desig- 

 nation, MuaciaaMcola striaticeps d'Orbigny and Lafresnaye. 



