On the Pacific coast it seems to be quite abundant, at different seasons, from Cape St. Lucas to the arctic regions, where it breeds. Mr. Kennicott obtained several specimens at Fort Yukon and at Fort Resolution, and Mr. Boss met with them at Fort Simpson. Xantus obtained these birds both at Fort Tejon and at Cape St. Lucas. It is common in Southern California during the winter, frequenting low bushes and the margins of streams. Dr. Gambel met with it in early spring on the island of Santa Catalina, where he had an opportunity of listening to its simple and lively song. This he describes as commencing in a low, sweet trill, and ending in _tshe-up_. It is sometimes considerably varied, but is described as generally resembling _er-r,r,r,r-shè-up_. Dr. Cooper speaks of this Warbler as an abundant and constant resident of California, near the coast, and found in summer throughout the Sierra Nevada. In March they begin to sing their simple trill, which, he says, is rather musical, and audible for a long distance. Dr. Coues met with this Warbler in Arizona, at Fort Yuma, September 17, at Fort Mohave, October 1, and also at the head-waters of Bill Williams River. Lieutenant Couch found it at Brownsville, Tex., seeking its food and making its home among the low shrubbery. Dr. Suckley found it very abundant at Fort Steilacoom, in Washington Territory, where it kept in shady places among thick brush, generally in the vicinity of watercourses. Dr. Heermann found a few pairs incubating near the summits of the highest mountains on the Colorado River. The nests of this species, seen by Mr. Kennicott, were uniformly on the ground, generally among clumps of low bushes, often in the side of a bank, and usually hidden by the dry leaves among which they were placed. He met with these nests in the middle of June in the vicinity of Great Slave Lake. They were large for the size of the bird, having an external diameter of four inches, and a height of two and a half, and appearing as if made of two or three distinct fabrics, one within the other, of nearly the same materials. The external portions of these nests were composed almost entirely of long, coarse strips of bark loosely interwoven with a few dry grasses and stems of plants. Within it is a more elaborately interwoven structure of finer dry grasses and mosses. These are softly and warmly lined with hair and fur of small animals. Nests from more arctic regions are of a different style of structure, homogeneous in materials,—which are chiefly stems of small plants and the finer grasses,—and are of a more compact make and smaller in size. Their eggs are from four to six in number, and vary in length from .70 to .60 of an inch, and in breadth from .50 to .45 of an inch. They have a clear white ground, marked with spots and small blotches of reddish-brown and fainter marking of purplish-slate. The number of spots varies greatly, some eggs being nearly unspotted, others profusely covered.