BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 349 



taken) ; Mendoza, Mendoza, March 13; Potrerillos, Mendoza, March 

 15 to 21 (five immature specimens) ; Timuyan, Mendoza, March 

 22 to 29 (immature female) ; Concon, Chile, April 24 to 27 (two). 

 House wrens seen at General E,oca, Rio Negro, November 23 to 

 December 3, may also have been this form. 



CISTOTHORUS PLATENSIS PLATENSIS (Latham) 



Sylvia platensis Latham, Index Orn., vol. 2, 1790, p. 548. (Buenos 

 Aires. ) 



At Lavalle, Buenos Aires, four adult males were taken October 

 23, 1920, while at Tunuyan, Mendoza, a series of 10, all immature 

 (both sexes represented), was secured between March 23 and 28, 

 1921. Hellmayiy in a review of this species, considers that tyj^ical 

 platensis ranges from Bahia Blanca north to Santa Elena, Entre 

 Eios, and west to Mendoza, Of the present series the skins from 

 near the mouth of the Kio Ajo, at Lavalle, may be considered as 

 topotypical of Latham's platensis from " Bonaria." The skins from 

 the Province of Mendoza are different, but as all are young must 

 be allotted to 2)Iate7isis until adult specimens may be examined. 

 All of the birds from Tunuyan appear slightly more heavily 

 streaked above, and have the dark tail bars broader than skins 

 from Lavalle. Half of those seen have the rump plain brownish 

 and the streaks on the crown nearly obsolete. In the remainder 

 the head is distinctly lineated; the back marldngs are heavier and 

 extend down over the rump. In a way these specimens appear 

 intermediate between C. p. homensis, which is very heavily marked 

 above from neck to upper tail coverts, and is strongly rufescent, 

 and platensis but are nearer the latter. It is probable that Cisto- 

 thoims fasciolatus Burmeister*^ may prove a valid subspecies. 



At Lavalle, Buenos Aires, I found a small colony of these marsh 

 wrens in low growths of dead rushes at the border of a tidal marsh, 

 where attention was attracted by their tinkling songs tu-tu-tu tee-tee- 

 tee ter-ter-ter tsee-ee-ee-ee^ each triplet being pitched in a slightly 

 different key, while the whole terminated in a metallic music-box 

 rattle. As the birds sang from the tops of rushes they were easily 

 located by their light breasts, but as I approached they dropped down 

 into heavy cover which they often refused to leave in spite of 

 various attractive noises, from the usual squeak to the low clinking of 

 a brass shell against a gun barrel, made to excite their curiosity. 

 Their flight was undulating, often at a height of li/^ to 2 meters 

 above the marsh. Near Tunu3'an, Mendoza marsh wrens were en- 



«Nov. Zool., vol. 28, September, 1921, p. 250. 

 *i Journ. fur Ornith., 1860, p. 2.52. (Mendoza.) 



54207—26 ^23 



