HIRUNDINIDA. 267 
as occurring on the Pacific slope of the continent. In the fact of 
its being a bird of the eastern province of the United States during 
summer, and in winter crossing the mountains of northern Mexico 
to the Pacific coast, it appears to resemble Dendroica dominica, 
Mniotilta varia, Larus atricilla, Sterna antillarum and anglica, etc., 
none of which are known on the California coast at any season. 
Dendroica chrysopareia. Page 183. 
Dr. Sclater has recently stated that the specimens referred to (p. 
185) as from San Antonio, Texas, are true D. chrysopareia, and 
thus the species is to be included in the fauna of the United States. 
Famity HIRUNDINID. 
Bill short, triangular, very broad at base (nearly as wide as long) and 
much depressed, narrowing rapidly to a compressed, notched tip; mouth 
opening nearly to the eyes. Primaries nine, graduating rapidly less from the 
exterior one; tail feathers twelve.! Feet weak; tarsi scutellate, shorter than 
middle toe and claw. Number of joints in toes normal; basal joint of middle 
toe partially or entirely adherent to lateral toes. Wings long, falcate. Tail 
forked. Eyessmall. Plumage compact, usually lustrous. All the American 
species with a white patch on the sides under the wing? 
The Hirundinidz form a very well marked group of birds easily 
distinguished from all others. They exhibit a close resemblance, in 
external appearance and habits, to the Cypselide ; from which, apart 
from the internal structure, they are readily distinguished by the 
possession of nine, instead of ten primaries; twelve, instead of ten 
tail feathers ; scutellate tarsi, toes with normal number of joints (1. 
2. 3. and 4., respectively, exclusive of ungual phalanges), instead of 
a different proportion; differently shaped nostrils, ete. In both 
families the wings are developed to an extraordinary degree; the 
outer primary nearly twice or more than twice the length of the 
inner, and enabling its possessor to sustain flight almost indefi- 
nitely. The relaticns of the family among the Oscines appear closest 
to the old-world IMWuscicapide. 
The precise character of scutellation of tarsus is somewhat difficult 
' Of the two specimens of Alticora fasciata before me, neither has more 
than ten tail feathers. I do not know whether this is characteristic of the 
species or not. 
