The nests of this Warbler, so far as has fallen under my observation, have always been made of long gray lichens still attached to the trees on which they grow. With great skill do these tiny architects gather up, fasten together, and interweave, one with the other, the hanging ends and longer branches. By an elaborate intertwining of these long fibres they form the principal part, sometimes the whole, of their nests. These structures are at once simple, beautiful, ingenious, and skilfully wrought. When first made, they are somewhat rude and unfinished, but as their family are gathered, the eggs deposited, incubated, and hatched, a change has been going on. Little by little has the male bird busied himself, when not procuring food for his mate, in improving, strengthening, and enlarging the nest. These same acts of improvement upon the original nests are noticed with Humming-Birds, Vireos, and a few other birds. The nests are sometimes constructed on the sides of trunks of trees, when covered with the long gray lichens, but are more frequently found hanging from branches usually not more than six or eight feet from the ground. Thus surrounded by long hanging mosses in clumps not distinguishable from the nests themselves, they would not be readily recognized were it not that those familiar with the habits of the bird may be readily guided to the spot by the artless movements of the unsuspecting parents. These birds are confiding, easily approached, and rarely exhibit any signs of alarm. Even when their nest is disturbed they make but little complaint, and do not manifest any very great signs of emotion. When built against a trunk these nests consist only of an interweaving of the moss above and below a very small opening, within which a small cup-shaped flooring has been made of the same material, and usually cannot be removed without destroying all semblance of a nest. When pensile they are imperfectly circular in shape, with an entrance on one side, and rarely with any lining. Occasionally they are models of symmetry and beauty. The eggs, four or five in number, have a clear white ground, and are sparingly spotted with markings of reddish-brown, slate, purple, and lilac. In some the first predominate, in other the last three shades are more abundant, and usually form a confluent ring around the larger end. They measure from .62 to .65 of an inch in length, and from .49 to .50 in breadth. SECTION SYLVICOLEÆ. This section has been already characterized as having a distinctly notched bill, well provided with bristles. Of the two genera one, _Perissoglossa_, has the bill slender, acute, something like _Helminthophaga_, and with the tongue lengthened and much lacerated at end; the other, _Dendroica_, with less acute bill and tongue shorter, merely notched at tip, and a little fringed only. GENUS PERISSOGLOSSA, BAIRD. _Perissoglossa_, BAIRD, Rev. Am. Birds, 1864, 181. (Type, _Motacilla tigrina_, GM.)