proved to be very abundant during the spring migration, particularly in the lower parts of the mountains; but the most of them seem to go farther north, and but few, compared with the numbers seen in April and the early part of May, remained through the summer to breed. The earliest arrival noted was on April 10th and soon after they were quite abundant, mostly in the oak region below 5000 feet, remaining so throughout April and up to the first week in May, at which time the migrating birds had about all passed on. All that were seen after that I took to be breeding birds, for they gradually moved to a higher altitude, (6000 to 8000 feet) and were nearly all in pairs. About the middle of April, 1902, I found a few _virginiae_, together with other migrating warblers, in the willows along the San Pedro River, some fifteen miles from the mountains. _Nesting._--Ridgway was evidently the first to record the nest of Virginia's warbler, finding it near Salt Lake City on June 9, 1869. "The nest was embedded in the deposits of dead or decaying leaves, on ground covered by dense oak-brush. Its rim was just even with the surface. It was built on the side of a narrow ravine at the bottom of which was a small stream. The nest itself is two inches in depth by three and a half in diameter. It consists of a loose but intricate interweaving of fine strips of the inner bark of the mountain mahogany, fine stems of grasses, roots, and mosses, and is lined with the same with the addition of the fur and hair of the smaller animals" (Baird, Brewer, and Ridgway, 1874). Shortly afterwards, a nest was found on June 1, 1873, in Colorado, by C. E. Aiken. It was reported by Aiken and Warren (1914) as "the first nest of this species known to science. * * * This was sunk in the ground in a tuft of bunch grass growing in a clump of oak brush, with the dead grass hanging over and completely concealing the nest, which was reached through a small round hole like a mouse hole through the protecting grass." Dr. Linsdale (1938) reports a nest found in Nevada, at an elevation of 7,700 feet, that "was at the lower edge of a clump of grass 20 inches tall and 2 feet across. The surrounding hillside was of small rocks lying at a maximum angle of rest. A few similar grass clumps were scattered near, about 10 feet apart. The surrounding trees were mountain mahogany and chokecherry. The nest was composed entirely of grass and was in a depression in the loose soil. It was well concealed by dead grass at the base of the tuft." In the Huachuca Mountains, Ariz., Mr. Swarth (1904) found a nest that "was built on a steep sidehill about ten feet from a much traveled trail, and was very well concealed; being under a thick bunch of overhanging grass, and sunk into the ground besides, so as to be entirely hid from view. This was at an elevation of about 8,000 feet, which seems to be about the upward limit for this species in this region."