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BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 353
MIMUS PATAGONICUS PATAGONICUS (d'Orbigmy and Lafresnaye)
Orpheus patagonicus d'OEBiGNY and Lafresnaye, Mag. Zool., 1837, cl. 2,
p. 19. (Patagonia.)
Two males and a female of the Patagonian mocking bird, in
slightly worn breeding dress, secured at General Roca, Rio Negro,
November 24 and 29, 1920, show the normal development of grayishbrown
ventral surface and cinnamon-buff flanks that characterize
the species. One when first killed bad the bill and tarsus black;
iris buffy brown.
This mocker was common in growths of atriplex {Atriplex lampa
and A. crenatifoNa) , creosote bush, and greasewoods on the flood
plain of the Rio Negro, near General Roca, and proved to be a true
desert form since it spread out through the arid, gravel hills north
of the railroad, where water was wholly lacking. On December
6 it was recorded from the train near Challaco, Neuquen (approxi-
mately 100 kilometers west of the town of Neuquen), but was not
found at Zapala.
These mockers watched alertly from the tops of bushes, or flew
ahead of me, showing a band of white, interrupted in the middle,
at the end of the tail. Their song, mockerli^'e in type, delivered
from some low perch, consisting of many broken phrases interspersed
with frequent imitations of the notes of other brush birds, was
similar to that of 31. triianis, though the performers were less flamboyant
in actions during delivery.
MIMUS PATAGONICUS TRICOSUS Wetmore and Peters
Mimus patagonicus tricosns Wetmore and Peters, Proc. Biol. Soc. Wash-
ington, vol. 36, May 1, 1923, p. 145. (Lujan de Cuyo, Province of
Mendoza, Mendoza.)
The present form is separated from typical patagonicus by its
grayer dorsal surface, a difference most evident in birds in fall and
winter plumage.
Two were observed near an old puesto above the city of Mendoza,
on March 15; and in the foothills of the Andes near Potrerillos,
Mendoza, the birds were common from March 15 to 19. An immature
male, taken at El Salto, at an elevation of 1,800 meters, on
March 19, is in post -juvenal molt.
MIMUS THENCA (Molina)
Turdus Thenca Molina, Sagg. Stor. Nat. Chili, 1782, p. 250. (Chile.)
Near Concon, Chile, M. thenca Vv'as common from April 24 to 28,
1921, and two specimens were taken. This species seems closely
allied to M. longicaudatus Tschudi ** of Peru, which may prove sub-
"Arch. fur Naturg., 1844, p. 280. (Peru.)