The ground-color of their eggs is white, and they are marked with dots,
blotches, and points of reddish-brown. These markings vary greatly in size, number, and distribution. They are usually chiefly about the larger end. In shape they are usually less elongated than those of the Barn Swallow, and their markings are larger. This is not, however, invariable, and the two kinds are not always distinguishable. In length they vary from .875 of an inch to .75, and their average breadth is .60.
Genus HIRUNDO, Linn.
Hirundo, Linn. Syst. Nat. I, 10th ed. 1758, 191. (Type, H. rustica, Linn.)
Hirundo horreorum.
1452
Under the generic head of Hirundo I propose to combine several groups of American Swallows agreeing in moderate, depressed bill, with straight commissure, and lateral nostrils overhung by membrane; the tarsi feathered only at the upper end, or else entirely bare; the lateral claws moderate, not extending beyond the base of the median; the edge of the outer primary without hooks; the tail variable in character, from a very deep fork to a slight emargination only.
Subgenera.
Tarsi slightly feathered on inner face at upper end; equal in length to middle toe without claw.
Tail very deeply forked … Hirundo.