The same observant naturalist, some time afterwards, in May, found the nest of another pair, a few miles north of Santa Clara. This was built near the foot of a mill-dam, resting on a slight ledge under an overhanging rock, from which water was continually dropping. It was, in shape, like an oven, with a small doorway, and it was built externally of green moss, which, being still living, prevented the easy discovery of the nest. It was lined with soft grass, and contained young. These birds are found singly or in pairs, and never more than two together. They are never found near still water, and frequent only wild mountain-streams, cascades, eddies, and swift currents. According to Mr. Dall’s observations in Alaska, the species is essentially solitary. He obtained several specimens in January, February, and March, always near some open, unfrozen spots in the Nulato River. It was only found in the most retired spots, and almost invariably alone. When disturbed, it would dive into the water, even in midwinter. Mr. Ridgway describes the Dipper as remarkably quick, as well as odd, in its movements,—whether walking in the shallow bed of the stream, or standing on a stone along the edge, continually tilting up and down, now chattering as it flies rapidly along the stream, again alighting into the water, in which it wades with the greatest facility. Its flight is remarkably swift and well sustained, and in manner is very unusual, the bird propelling itself by a rapid buzzing of the wings, following in its flight every undulation in the course of the stream into which it drops suddenly. Its song is described as remarkably sweet and lively, in modulation resembling somewhat that of the _Harporhynchus rufus_, but less powerful, though sweeter in effect. Dr. E. Baldamus, of Halle, who possesses specimens of the eggs of this species, describes them as pure white in color, oval in shape, and hardly distinguishable from those of the European _C. aquaticus_. A nest of this bird obtained by Mr. J. Stevenson, of Hayden’s Expedition, in Berthoud’s Pass, Colorado, is a hemisphere of very uniform contour built on a rock, on the edge of a stream. Externally it was composed of green moss, in a living state; within is a strong, compactly built apartment, arched over, and supported by twigs, with a cup-like depression at the bottom, hemispherical and composed of roots and twigs firmly bound together. The structure is 7 inches in height externally, and has a diameter of 10½ inches at the base. Within, the cavity has a depth of 6 inches; the entrance, which is on one side, is 3½ in breadth by 2½ in height. The eggs were three in number, uniform, dull white, and unspotted. They measure 1.04 inches by .70. They have an elongated oval shape, and are much pointed at one end. FAMILY SAXICOLIDÆ.—THE SAXICOLAS.