Bulletin - United States National Museum - si-pddr - Smithsonian ...

BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 291
bonariensis) . The
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two white eggs measure, respectively, in milli-
meters, 24.5 by 18.3 and 27.3 by 20.5. The smaller egg has a glossier,
more irregular surface than the large one, which is smoother and
dull in color. The difference in size and appearance between the
two is so striking that I believe that the larger egg alone is that of
RMnocryfta^ and that the smaller one was deposited in the nest by
some Synallaods. The parent {R. lanceolata) slipped down from
the nest through the branches to the ground; when secured, to my
surprise, it was a male.
Near Mendoza, Mendoza, this species was fairly common on March
13, 1921, but was very shy. At Potrerillos, Mendoza, it was recorded
on March 17, and several were seen and a female taken at El Salto, at
an elevation of 1,800 meters. Others were recorded on March 27
below Tunuyan, Mendoza, through a low range of sandy hills east of
the Rio Tunuyan. In fall the birds were much shyer than during the
breeding season, and, though their notes were heard, it was only by
chance that one was seen as it ran across some little opening in the
brush. Usually they took care to edge aside without exposing themselves.
The fall specimen secured is brighter, bufRer brown above
and on the flanks and under tail coverts than summer birds,
but is otherwise similar. The difference in color is attributed to the
fact that this bird is in fresh fall plumage, while the others are somewhat
worn.
An adult male, taken November 27, had the maxilla and tip of
mandible dull black ; base of mandible, neutral gray ; iris, Vandyke
brown; tarsus and toes, black.
TELEDROMAS FUSCUS (Sclater and Salvin)
Rhinocrypta fusca Sclateb and Salvin, Nom. Av. Neotr., 1873, p. 161.
( Mendoza.
Near General Roca, Rio Negro, the barrancolino, as this tapaculo
is known, was fairly common from November 25 to December 2.
1920. Adult males, preserved as skins, were taken on November 25
and 26, and a female on November 26. The species was found in
low, open brush over the dry gravel hills that bordered the level
valley of the Rio Negro, in a region wholly without permanent
water. As I passed along the shallow, steep-walled barrancas that
traversed this area, I had an occasional glimpse of a wrenlike bird
of moderate size, as, with tail cocked over its back, it sprinted away
over open ground, swerving constantly behind low clumps of vege-
tation for protection. Like snowy plover the birds ran on and on
and on long after one might expect them to stop, and hard running
was required on the part of the collector in order to keep up with
them. At other times as I cared for specimens that I had shot one