They are described as running gracefully on the ground, at times squatting to observe the movements of the intruders, and again elevating their bodies as if to meet their approach. Rising from the ground, they fly in an undulating manner, so that it is extremely difficult to shoot them on the wing. They continue thus to fly in increasing circles until about a hundred yards high, when they begin to sing. After a while, suddenly closing their wings, they drop to the ground. They could be easily approached in a light wagon, and in this manner several specimens were obtained. Captain Blakiston (Ibis, V. 61) found this Skylark common on the prairies of the Saskatchewan during the breeding-season. He first met with it on the 6th of May, near Fort Carlton. When disturbed from the grass, its usual haunt, it utters a single chirp, and immediately mounts in the air by a circuitous course, with a very undulating flight, to a great height, where with outstretched wings it soars in a peculiar manner, and utters a very striking song. This is described as consisting of a quick succession of notes, in a descending scale, each note being lower than the preceding. The bird then descends to the ground with great rapidity, almost like a stone, and somewhat in the manner of a hawk swooping on its prey. It was difficult of approach, and not easily killed. He also observed these birds in Northern Minnesota, May 4, 1859. A nest of this bird was built on the ground and placed in a hollow. It was made of fine grasses interwoven into a circular form, but without any lining. The eggs were four or five in number, an oblong oval in shape, much pointed at one end, and measuring .87 of an inch in length by .63 in breadth. Their ground-color was a dull white, so minutely dotted with a grayish-purple as to give the whole egg a homogeneous appearance, as of that uniform color. The young larks, soon after being hatched, followed their parents on the ground, and were fed with seeds of the smaller plants and with insects. They had already begun to associate in small flocks of from eight to a dozen before the party left, and on the 16th of August had commenced their southern migrations. FAMILY SYLVICOLIDÆ.—THE WARBLERS. The _Sylvicolidæ_ are essentially characterized among the Oscines with nine primaries, by their small size, the usually slender and conical insectivorous bill, shorter than the head, without angle in the gape near the base; the toes deeply cleft so as to leave the inner one free almost to its very base (except in _Mniotiltæ_), etc. The shallow notch at the end of the tongue, instead of a deeply fissured tip, distinguishes the family from the _Cærebidæ_, to some of which there is otherwise so great a resemblance. The absence of abrupt hook and notch in both mandibles separates it from such of the _Vireonidæ_ as have nine primaries.