Hab.—Rocky hill-sides in rich woods, especially where black leaf-mold has gathered between masses of rock; one of our most abundant and characteristic ferns, confined to North America, but extending from New Brunswick to Central Alabama, Professor Eugene A. Smith; westward to Arkansas, Professor F. L. Harvey; Wisconsin, Parry, T. J. Hale; and brought from the Saskatchewan and the Rocky Mountains of British America by Drummond. Description:—Professor Robinson has remarked of this species:—“This comes nearer being a tree fern than any other of our species; the caudex, covered by the bases of fronds of previous seasons, sometimes resting on bare rocks for four or five inches without roots or fronds.” The root-stock is much like that of _A. Filix-mas_, being very stout-closely covered with persistent stalk-bases and very chaffy. The chaff really grows mainly on the bases of the stalks, or covers the closely coiled buds which crown the root-stock. It is composed of shining ferruginous-brown thin lanceolate acuminate scales fully an inch in length, and destitute of a thickened midnerve. The fronds grow in elegant crowns from the apex of the root-stock, some six or eight or perhaps ten to a plant. The stalks vary in length, but are seldom more than a foot long. They are rather stout, round, but with a slight furrow in front, commonly reddish-brown in color, fading when dry to straw-color, and contain five or seven roundish fibro-vascular bundles, of which the two anterior ones are largest, and the next two the smallest. The outline of the fronds is ovate-lanceolate, varying to oblong-lanceolate. The frond is commonly not quite so wide at the base as in the middle, though in small specimens the base is often the widest. The texture is thicker than in any other of our Wood-ferns, and the fronds are fairly evergreen, not withering until the next year’s fronds begin to uncoil. In cutting, the fronds vary from pinnate, with pinnatifid pinnæ and short nearly entire lobes, to twice pinnate, with pinnately-lobed segments. In the example selected for our plate the pinnules are oblong, obtuse and crenulate, or at most, crenately-toothed. Other, and perhaps no larger, fronds will have most of the pinnules twice or even thrice as long as these, ovate-lanceolate and pointed, narrowed to a sub-cordate and obscurely-stalked base, and deeply pinnately-lobed. This is var. _elegans_ of Professor Robinson. Professor Lawson has a var. _Traillæ_, which has “very large bipinnate fronds, all the pinnules pinnatifid.” A very common form noticed by Mr. L. M. Underwood in Bulletin of the Torrey Botanical Club, has fronds only four or five inches long, the lower pinnæ only pinnatifid and the upper ones lobed, the sori mostly solitary on the lobes.