10G NORTH AMERICAN OOLOGY. PART I. 



are often exposed to great inclemencies of weather, from which they take refuge in 

 their holes. 



They are a very social species, almost always breeding together in large communi- 

 ties, of hundreds, and even of thousands. They seem more independent of man than 

 many of their kindred genera, only availing themselves of the incidental aid they 

 may derive from excavations through sand-banks, opening convenient situations for 

 their nests. These they construct in holes in the sides of banks, or cliffs, of sand, 

 soft earth, and even of gravel, wherever the passage of a stream of water, the wash- 

 ing of waves, excavations for canals or railroads, or any similar exposure of conven- 

 ient sites, afford them opportunities. These holes are usually as near the surface of 

 the ground as the yielding nature of the soil will permit it to be readily penetrated, 

 generally from two to five feet. They extend to a depth of from three to four 

 feet, seldom less than two, or more than four. Their diameter is from three to 

 four inches. In excavating such long channels to their nests, these little birds ex- 

 hibit a remarkable industry and perseverance. After selecting the place, both sexes 

 work alternately at the task, which usually occupies them four days of constant 

 labor. The extremity of the passage is widened into a small chamber, the floor of 

 which is warmly carpeted with fine dry grass, and soft, downy feathers. Upon this 

 they deposit five beautiful crystal-white eggs. When recently deposited and un- 

 blown, the yolk, seen through the semi-transparent shell, imparts to it a delicate ro- 

 seate shade. The eggs vary considerably in size and shape. Their length is from 

 li t If of an inch, the average |-|. Their breadth also varies from 4- to -% of an 

 inch. In shape they are often as nearly oval as the eggs of the Swift, but generally 

 one end is much more pointed than the other. 



In regard to its geographical distribution, but little needs to be said. It is prob- 

 ably found throughout North America, from Cuba, where both Mr. Lembeye and 

 Dr. Gundlach speak of it as common, to the mouth of Mackenzie's River, latitude 

 68 north. If identical with the Sand Martin of Europe, &c., it is found in all the 

 four quarters of the globe. It is as abundant on the Pacific as on the Atlantic, and, 

 according to Sir John Richardson, is as common in the Arctic regions as in the more 

 temperate. 



COTYLE SERRIPENNIS. 



Hirundo serripennis, AUD. Orn. Biog. IV, 1835, 593. 



" Syn. 1839, p. 37. 



" " " Birds of Am. I, 1840, 193, pi. li. 



Cotyle serripennis, CASSIN, Syn. N. A. Birds (Illust. Birds of Cal.), 1854, p. 247. 



VULG. The Rough-winged Swallow. 



MUCH yet remains to be learned of the habits and geographical distribution of this 

 species ; so closely resembling the Bank Swallow in many respects as to be liable 



