700 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 
STREPTOPROCNE ZONARIS MEXICANA Ridgway. 
MEXICAN COLLARED SWIFT. 
Similar to 8. z. albicincta, but averaging decidedly larger, general 
color much duller (less bluish) black, and forehead always distinctly 
grayish sooty; similar also to S. 2. zonaris,* but averaging smaller 
and coloration less uniform, the forehead and chin always distinctly 
paler than rest of head. 
Adults (sexes alike)—General color plain black or sooty black 
above, slightly more sooty below and decidedly more so on fore- 
head, chin, and throat, interrupted by a conspicuous collar of white 
(this broadest on chest), the feathers of this white collar dark sooty 
brown or dusky basally; bill black; iris dark brown; legs and feet 
dusky (more or less livid in life %). 
Immature.—Similar to adults, but white collar more or less broken 
by larger dusky central areas to feathers (especially on chest), and 
(in younger specimens) feathers of chin and upper throat streaked, 
those of lower throat tipped with whitish, and those of breast and 
abdomen and marginal under wing-coverts terminally margined with 
whitish. 
Young.—Much duller in color than adults, the under parts grayish 
sooty anteriorly, dark sooty posteriorly; white collar developed only 
on hindneck (where feathers are rather narrowly tipped with white), 
the feathers of chest very narrowly margined terminally with white; 
otherwise like the immature stage, described above. 
Adult male—tLength (skins), 183-225 (206.5); wing, 200-215 
(206.4); tail, 66.5-81.5 (75.6); exposed culmen, 8.5-10.5 (9.6); 
tarsus, 20.5-24 (22.3); middle toe, 14.5-16.5 (15.2).¢ 
Adult female.—Length (skins), 187-222 (207); wing, 194.5-206.5 
(200.5); tail, 62-79 (72); exposed culmen, 9-10.5 (9.8); tarsus, 
20.5-24 (22); middle toe, 14-16 (15).° 
@ Of southern Brazil and Argentina; see p. 697. 5 Fourteen specimens. 
Ex- ‘ 
Locality. Wing. | Tail. | posed | Tarsus. rs 
lculmen, 7 
MALES. 
Ten adult males from Mexico...............2.20-2226 2022s eee ee 205.5 75.6 9.5 22.5 15.2 
Two adult males from Guatemala...........-..2.... 02. ee ee eee 211.7 79 10 23 15.2 
Two adult males from British Honduras..................-..-- 205.5 72.2 9.7 22 15.2 
FEMALES. 
Ten adult females from Mexico........-.----.0----+22eeee eee 200.3 73.1 9.7 22.8 15.2 
Three adult females from Guatemala (2) and Chiapas (1)....... 202.5 71.5 10 21.5 14.7 
One adult female from British Honduras........-...-.------+- 194.5 62 10 20.5 15 
