In shape and general plan of construction the nest closely resembles that of a Baltimore Oriole. It has no hole in the side but instead a wide-mouthed opening at the top through which the bird entered it as the Oriole enters her nest. The upper edges and sides were securely fastened to the fine terminal twigs of a drooping branch where the nest hung suspended among the evergreen foliage of the hemlock, precisely as the Oriole's hammock swings in the dropping spray of an elm. The Warbler's nest has a scanty lining of pine needles and fine grasses but it is otherwise composed entirely of _Usnea_, loosely woven or perhaps merely felted together, evidently by the parent birds. They must have been at some pains to collect this material, for the closest scrutiny on the part of a friend and myself failed to reveal more than a few small and scattered tufts of _Usnea_ in the surrounding woods. Henry Mousley (1924, 1926, and 1928), of Hatley, Quebec, made three attempts to make complete studies of the home life of the northern parula warbler, none of which covered the whole cycle for reasons beyond his control. The nests were suspended from the branches of coniferous trees, at heights ranging from 26 feet in a spruce to 40 feet in a balsam fir. One of these nests was watched for a total of 24 hours, from May 22 to 31, during the process of construction; during this time the male sang 549 times from a little birch and went with the female to the nest, but brought no material; the female, however, made 206 trips with material, an average of one load every 5.4 minutes. The nest was made entirely of _Usnea_, all brought in, and lined with "some black hair-like rootlets, with two bits of plant down"; it was strengthened with a few fine grass stems. It weighed only 100 grains, or .23 ounce! "Outside diameter 3.25, inside 1.75 inches; outside depth 2.50, inside 1.75 inches. The female after selecting some of the longest threads of the hanging bunch of _Usnea_, attached them to a little twig a few inches off, following this up with that curious process--inherent--of moulding the nest, which in this case, was really an acrobatic performance, there being of course no apparent nest to mould, just a few strands, through which the bird's tail and wings protruded."