508 HISTORY OF THE 



prefer to make their homes with man, but, from choice, more re- 

 mote from his habitations. In flight they are rapid, but rather 

 unsteady and fluttering. In their search for flies, etc., they 

 skim low over the Land and water, much like others of the tribe. 

 Their voice is a low, muttering twitter. They are social birds, 

 and breed together in communities, and are, therefore, local in 

 their distribution. They select for their breeding places the per- 

 pendicular sides of banks along the streams, or any steep em- 

 bankment where the soil is sufficiently soft to enable them to 

 excavate with their bills holes for their nests, which are usually 

 near the top, and about three feet in depth, but in gravelly soil 

 have been known to go great distances, or until a place free from 

 stones overhead has been reached (this is evidently to prevent 

 injury to their eggs or young from falling earth or pebbles), 

 the end worked out oven shaped, and lined with fine grasses and 

 feathers. In favorable situations the holes are near together, 

 and in large communities the banks are honeycombed. Eggs 

 four to six, .69X.49 (they vary in size); pure white; when un- 

 blown have a rosy hue; in form, oval. 



Genus STELGIDOPTERYX Baird. 



♦'Bill rather small; nostrils oval, superior, margined behind (but scarcely 

 laterally) by membrane, but not at all overhung; the axes of the outline converg- 

 ing. Frontal feathers soft and ( like chin) without bristles. Tarsi equal to middle 

 toe without claw; the upper end covered with feathers all round; none at lower 

 end. Basal joint of middle toe adherent externally nearly to end; internally, 

 scarcely half. Lateral toes about equal, their claws not reaching beyond base 

 of middle claw. Tail slightly emargluate; the feathers broad, and obliquely 

 rounded at end. Edge of the wing rough to the touch; the shafts of the fibrillse 

 of outer web of outer primary prolonged, and bent at right angles into a short, 

 stiff hook. 



"The great peculiarity of this genus consists in the remarkable roughness of 

 the edge of the wing (said to occur also in Psalidoprocne, Cab.). The object is 

 uncertain, but is probably to enable the bird to secure a foothold on vertical or 

 inclined rocks, among or on which it makes its nest. A favorite breeding place 

 of S. serripennis is in the piers and abutments of bridges, and these hooks might 

 render essential aid in entering into their holes." 



