BIRDS OF NORTH AND MIDDLE AMERICA, 541 
Bill longer than head, large and stout, the exposed culmen more 
than one-fifth as long as wing; gonys much shorter than mandibular 
rami, straight or very nearly so, its basal angle not prominent; 
depth of bill at base equal to nearly one-fourth the length of com- 
missure; nostril elliptical, narrower posteriorly, separated from the 
nearest loral feathering by a space much greater than length of 
nostril; anterior outline of feathering on head without indentation 
at base of culmen, where truncated or slightly convex, sloping thence 
downward and backward to the rictus, sometimes with a very smell 
projecting angle (latero-frontal antia) on each side of base of culmen. 
Wing long and pointed, the longest primary (outermost) exceeding 
distal secondaries by nearly twice the distance from tips of the latter 
to bend of wing. Tail much less than half as long as wing, forked 
for about one-fourth its length, the lateral rectrices rather abruptly 
contracted, but not acuminate, terminally. Tarsus longer than 
middle toe without claw (but shorter than middle tow with claw); 
webs between anterior toes with anterior edge slightly incised. 
Plumage and coloration.—Plumage distinctly blended only on 
pileum. Adults with pileum, nape and auricular region black (the 
feathers tipped with white in post-nuptial plumage), the rest of 
upper parts grayish brown or brownish gray, the distal wing-coverts 
and under parts white. 
Range.—South America; accidental in Cuba. (Monotypic.) 
PHZATUSA CHLORIPODA (Vieillot). 
LARGE-BILLED TERN. 
Adults in breeding plumage (sexes alike)—Pileum, nape, and 
auricular region uniform black, this descending to anterior angle of 
eye and extending along median line of hindneck; back, scapulars, 
proximal wing-coverts, tertials, rump, upper tail-coverts, and’ tail 
plain deep neutral gray; distal smaller wing-coverts, secondaries, greater 
* wing-coverts, lores (sometimes anterior margin of forehead, narrowly), 
and under parts immaculate white, the sides and flanks more or less 
strongly tinged with pale or pallid neutral gray, the sides of neck 
deeper gray; primary coverts and primaries dull black, the innermost 
primaries with inner webs more grayish and margined terminally 
with white; inner webs of primaries with an extensive white “wedge,” 
especially the outermost; bill yellow, more or less tinged with grayish 
or horn color basally; legs and feet grayish dusky (said to be olive, 
with yellow webs, in life). 
Adults in post-nuptial plumage’—Similar to breeding adults, but 
feathers of the black pileum tipped with grayish white. 
Immature.—Essentially like adults but pileum light gray, deepen- 
ing into black on auricular region and near anterior angle of eye; 
back, etc., pale gray (between light neutral gray and light mouse 
