308 U. S&S P. R. R. EXP. AND SURVEYS—-ZOOLOGY—GENERAL REPORT. 
Tail moderately forked. Beneath entirely white. Above uniform lustrous green. 
P. bicolor. 
Hirundo bicolor has by some authors been placed under Chelidon, but is readily distinguished 
by having the tarsi and toes smooth, instead of feathered. 
Cabanis has established a genus, Yachycineta,! for the violet green swallow, H. thalassina, on 
account of its rather forked tail and small bill, and the entire absence of gloss on the feathers. 
He, however, includes in it the H. bicolor, which is remarkable for the lustre of its dorsal 
plumage. For the purposes of the present report it will be sufficient to consider them under 
the same head. 
HIRUNDO HORREORUM,? Barton. 
Barn Swallow. 
Hirundo horreorum, Barton, Fragments N. H. Penna. 1799,17. 
Hirundo rufa, Vierttot, Ois. Am. Sept. I, 1807, 60; pl. xxx. (Not of Gmelin.)—Cassin, Ulust. I, 1855, 243.— 
Brewer, N. Am. Ool. I, 1857, 91; pl. v, f. 63—67, eggs. 
Hirundo americana, Witson, Am. Orn. V, 1812, 34; pl. xxxviii, f. !, 2. (Not of Gmelin.)—Ricu. F. B. A. U, 
1831, 329. 
Hirundo rustica, AupuBon, Orn. Biog. II, 1834, 413; pl. 173.—Is. Syn. 1839, 35.—Is. Birds Am. I, 1840, 181; pl. 
48. (Not of Linnaeus.) 
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Sp. Cu.—Tail very deeply forked; outer feathers several inches longer than the inner, very narrow towards the end. Above 
glossy blue, with concealed white in the middle of the back. Throat chestnut ; rest of lower part reddish white, not conspicu- 
ously different. A steel blue collar on the upper part of the breast, interrupted in the middle. Tail feathers with a white spot 
near the middle, on the inner web. Female with the outer tail feather not quite so long. Length, 6.90 inches; wing, 5.00; 
tail, 4.50. 
Hab.—North America from Atlantic to Pacific. 
Specimens from the far west have the same general appearance as eastern ones, except that 
one (6619) from the Sacramento valley is the largest I have seen, with the tail half an inch 
longer than in Carlisle specimens. 
There is not much variation in skins of this species, except, perhaps, in the intensity of the 
coloration on the belly. In some specimens (1452) there is very little difference between the 
throat and abdomen, the former a little more chestnut. Sometimes the belly is nearly white 
with a slight tinge of brown. Occasionally the black collar on the throat is continuous across, 
along a single line of feathers. In one (2191) there is a broad collar across the throat as wide 
as in the European species, interrupted, however, in its central portion by dull chestnut. e 
The female is much like the male, but has the external tail feathers less elongated. In the 
young the tail is simply deeply emarginate, not forked as in the adult. 
Specimens from Texas and northern Mexico are smaller than those found further north. 
This species resembles the European Barn Swallow; in which, however, the pectoral collar 
is continuous across and quite broad, and the belly more rufous, with other differences. 
The determination of the true specific name of this species is a matter of some uncertainty, 
depending upon whether the South American bird be distinct from the North American or not. 
7 Museum Heineanum, 1850, 48. 
2 The following synonyms refer to the South American species : 
Hirundo erythrogaster, Bopparrt, Tableau Pl. enl. 724, f. 1, 1783, 45. 
Hirundo rufa, Gmein, Syst. Nat. I, 1788, 1018. 
Hirwndo cyanopyrrha, ViritL0ot, Nouv. Dict. XIV, 1817, 510. 
Hirondelle a ventre roux de Cayenne, Burron, Ois. VI, 607.—Iz. pl. enl. 724, f. 1. 
