258 ORNITHOLOGY AND OOLOGY. 
about ten rods square, I counted over fifty. Of course, the 
‘birds were in myriads, and the species constitutes the com- 
mon Swallow of the districts in that latitude. The materials 
used in the construction of the nest are fine grasses, hay, 
and feathers: these are adjusted loosely in the cavity of the 
tree, and without any form. The eggs are, most commonly, 
five in number. ‘Their color is a beautiful clear-white, with 
a roseate tint before their contents are removed: they are 
extremely thin and fragile, much more so than most of the 
other species; and their form is a slender oval. Of a great 
number of specimens, collected in various localities, the 
largest is .79 by .56 inch; the smallest, .69 by .51 inch. 
Two broods are generally reared in the season, and the 
period of incubation is fourteen days. 
This species leaves New England in the fall migration 
about the 10th of September. 
COTYLE, Botr. 
Cotyle, Born, Isis (1822), 550. (Type H. riparia.) 
Bill very flat, extremely broad at the base, and gradually narrowed towards 
the tip; nostrils prominent and rounded; tail moderate, nearly straight, or some- 
what emarginated; tarsi rather shorter than the middle toe, slender and scutellated; 
toes very slender, the claws slightly curved; colors generally dull brown above, 
without gloss. 
COTYLE RIPARIA. — Boie. 
The Bank Swallow. 
Hirundo riparia, Linneeus. Syst. Nat., I. (1766) 344. Wils. Am. Orn., V. 46. 
Aud. Orn. Biog., IV. (1838) 584. 
Cotyle riparia, Boie. Isis (1822), 550. 
DESCRIPTION. 
The smallest of American swallows; tail slightly emarginate; outer web of first 
primary soft, without hooks; lower part of the tarsus with a few scattered feathers; 
above grayish-brown, somewhat fuliginous, with a tendency to paler margins to the 
feathers; beneath pure-white, with a band across the breast and sides of the body 
like the back. 
Length, four and seventy-five one-hundredths inches; wing, four; tail, two 
inches. 
