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140 BULLETIN 133^ UNITED STATES NATIONAL MUSEUM
the small indentation of the Bahia de Samborombon into which it
opens, below Lavalle, Buenos Aires. On January 9, 1921, 40 or
more were recorded at Carrasco, a bathing resort a few kilometers
east of Montevideo, Uruguay, and on January 16 others were seen
in the same locality. The male secured had the soft parts colored
as follows: Bill, between flesh-ocher and rufous; iris, natal brown;
tarsus, black with a few of the scutes marked with vinaceous russet
underside of toes, ochraceous orange. The bird was in full plumage.
PHAETUSA SIMPLEX CHLOROPODA (Vieillot)
Sterna chloropoda Vieillot, Nouv. Diet. Hist. Nat., vol. 32, 1819, p. 171.
(Paraguay.)
The large-billed tern was fairly common near the Rio Paraguay.
At Las Palmas, Chaco, it was seen in small numbers about lagoons
from July 23 to 31. On July 26 two were observed resting on a flat
clump of grass and one, an adult female, was taken. At Puerto
Pinasco several were observed over the Paraguay River on Septenj-
ber 3, and from September 6 to 21 occasional birds were recorded
west of that point at lagoons near the ranch at Kilometer 80. They
were seen frequently in steamer travel along the river, the last being
noted at Villa Concepcion, Paragua}^, on October 3.
These birds on the wing appear more robust than other terns, an
appearance heightened by the strong, heavy bill. They frequenth'
swing up to an intruder and examine him curiously or scold vigor-
ously with harsh raucous calls. At such times the light-colored bill
is prominent.
The soft parts in the adult female secured were colored as follows
Bill lemon chrome, becoming light cadmium at base of culmen;
tongue and inside of bill lemon chrome, becoming cress green toward
the fauces ; iris fuscous ; tarsus and toes primuline yellow ; claws dull
black at tip, changing at base to gray number 7.
Large-billed terns from the northern portion of South America
have the upper surface varying from darker than neutral gray to
dark neutral gray, while in specimens from Paraguay and northern
Argentina (Chaco) the hind neck, back, scapulars, lesser wing
coverts, and tail are between light neutral gray and neutral gray.
The evident differences separate birds from the two regions as wellmarked
subspecies.
/Sterna simplex of Gmelin ^^ has been referred doubtfully to the
present species by several writers. It is based on the simple tern of
Latham ^^ from Cayenne. Turning to the original citation in
Latham it is found that the bird described is evidently in immature
plumage. The points given agree perfectly with those of the young
18 Syst. Nat., vol. 1, pt. 2, 1789, p. 606.
'9 Gen. Syn. Birds, vol. 3, pt. 2, 1785, p. 355.
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