HIRUNDO. 299 
Hirundo thalassima. 
Hirundo thalassina, Swainson, Phil. Mag. I, 1827, 365 (Mexico).—Aup. 
Orn. Biog. IV, pl. 385.—Is. B. A. I, pl. 46.—Brewer, N. A. Ool. 
I, 1857, 102 (the fig. pl. v, fig. 74 of egg belongs to another species). 
—Bairp, Birds N. Am. 1858, 311.—Maxam. Cab. Jour. 1858, 101. 
—Lorp, Pr. R. A. Inst. Woolw. IV. 1864, 115 (Vancouver Isl. ; nests 
in holes of trees).—Coorer & Suckury, P. R. R. Rep. XII, m, 185 
(W. T.).—Chelidon thalassina, Bore, Isis, 1844, 171.—Tachycineta 
thalassina, Cas. Mus. Hein. 1850, 48.—Petrochelidon thalassina, 
Scrater & Sanyiy, Ibis, 1859, 13 (Guatemala).—Scuater, Catal. 
1861, 39, no. 239.—Is. P. Z. 8. 1864, 173 (City Mex.) 
Hab. Western and middle provinces of United States, south to Guatemala. 
Specimens from different localities, as well as from the same place, 
vary somewhat in the shade of coloration. Sometimes, as in other 
Swallows, the innermost secondaries are edged and tipped with 
white, more or less conspicuously. Young birds are uniform lustre- 
less grayish-brown above, something like Cotyle riparia, white 
below, with perhaps a tinge of ashy across breast; the upper sur- 
face of wings and tail with a greenish gloss; the whole side of 
head, including loral region and around the eye, dusky, not white as 
in the adult. The white feathers on the posterior inner face of the 
tarsus are more conspicuous than in the adult, and reach nearly two- 
thirds the way to the toes, but do not exist at the lower end as in 
Cotyle riparia, which at once distinguishes them. All the feathers 
of under parts, even of chin and throat, are gray at base, not white; 
those of breast plumbeous to near tips, with a central stripe of lighter 
(concealed). 
Specimens (probably resident) from Cape St. Lucas are much 
smaller than from Upper California, the wing measuring 3.95, the 
tail 1.90 inches, while 1,895 measures 4.50 and 2.20, respectively. 
No. 29,204, from a typical locality (Orizaba), measures 4.70 and 
2.40. 
The fully fledged young bird differs so much in appearance from 
the adult, that I was at one time inclined to consider them as differ- 
emt species. ‘The female is duller than the male, especially on the 
head and rump. 
