BIKDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 49 



Near General Roca, Rio Negro, on November 27, one was seen 

 breasting the swift current of the Rio Negro in main stream. On 

 January 9, 1921, in the mouth of the Arroyo Carrasco, below Monte- 

 video, I found two pairs apparently on their breeding grounds. 

 When I first arrived only two grebes were visible, but these were 

 joined at once by two others, one of which came sliding out from the 

 reeds on the opposite bank. The birds, handsome in their full 

 plumage, swam back and forth with arching necks and raised crests, 

 finally diving as I came out from cover of the bushes. Two others 

 were seen offshore in salt water opposite Carrasco on January 16. 

 while near Lazcano, Department of Rocha, Uruguay, two in full 

 plumage were noted February 7. On March 4 one was recorded on 

 the Laguna del Monte at Guamini, Province of Buenos Aires, Ar- 

 gentina. 



It is probable that birds from Patagonia and Chile may be sep- 

 arated from those from Buenos Aires, and farther north by smaller 

 size, smaller, more slender bills, and in adult plumage, by grayer hind 

 neck. The series at hand, however, is insufficient to make these 

 points certain. 



PODILYMBUS PODICEPS ANTARCTICUS (Lesson) 

 Podiceps antarcticus Lesson, Rev. Zool., July, 1842, p. 209. (Valparaiso.) 



The pied-billed grebe of southern South America may be segre- 

 gated from typical podiceps of North America as a subspecies under 

 the name antarcticus of Lesson, on the basis of average grayer colora- 

 tion above, including sides of neck, and more brownish hind neck. 

 It is a large robust form with strong, heavy bill. Specimens have 

 been examined from Buenos Aires, Rio Negro, and Chubut, Ar- 

 gentina, and Santiago, Chile, but whether this form covers the whole 

 of South America remains to be determined. Females of this species 

 in breeding dress may be distinguished from males by the greater 

 extent of the dusky markings on the feathers of the undersurface, 

 especially on the lower breast and abdomen, so that they appear 

 much darker, a point that needs attention in making comparisons. 

 Following are measurements, in millimeters, of three specimens taken 

 near General Roca, in the Territory of Rio Negro, Argentina : Two 

 males, wing 136.5, 145.0; culmen, 25.6, 25.0; tarsus, 45.5, 46.0; one 

 female, wing, 133.8 ; culmen, 22.5 ; tarsus 42.5. 



Near Lavalle, Province of Buenos Aires, from October 30 to No- 

 vember 9, pied-billed grebes were seen at intervals in pools in the 

 marshes. They were very shy and seemed to be on their breeding 

 grounds. At General Roca, in Rio Negro, they were found in the 

 quiet water of narrow lagoons, bordering the present channel of 

 the river. On November 30 I killed three here, a mated pair and a 

 fully grown male still in immature plumage. The adult male taken 



