Description:—This belongs to the same group of species as _P. Wrightiana_, _brachyptera_ and _Ornithopus_. It has the same nodose and scaly root-stock, dark and polished stalk, glaucescent frond and mucronulate pinnules. In Mexico, South America and the Hawaiian Islands it never occurs with more than trifoliolate pinnules, and this is perhaps the best reason for considering _P. Wrightiana_ a distinct species. The pinnæ are tripartite rather than trifoliolate, while in the other fern just referred to, when trifoliolate the odd pinnule is more distinct and usually stalked, a distinction indicated by Hooker, but for which I am more indebted to the accurate discrimination of Mr. Faxon. In more southern localities the fronds are considerably larger than Dr. Hayes’ specimens, and the segments of the pinnæ ampler. In very dry seasons the pinnæ are considerably deflexed. The spores are trivittate as in the related species. PELLÆA ATROPURPUREA, Link. Clayton’s Cliff-Brake. Pellæa atropurpurea:—Root-stock short, knotted, chaffy with very narrow long-pointed soft cinnamon-brown scales; stalks four to eight inches high, terete, wiry, dark-purple or reddish-black, polished or more or less pubescent with paleaceous hairs; fronds six to twelve inches long, ovate or oblong-lanceolate in outline, evergreen, sub-coriaceous, pinnate, usually twice pinnate near the base; rachises smooth or hairy; pinnæ four to twelve pairs, the lower ones long-stalked, and divided into five to nine pinnules; upper pinnæ and the pinnules nearly sessile; oval to linear-oblong, at the base truncate or sub-cordate or sometimes hastate, obtuse or obtusely mucronulate, terminal ones longest; veins obscure, mostly twice forked; involucre rather broad, formed of the continuously recurved margin, paler and membranaceous on the edge, not fully covering the ripened sporangia. _Pellæa atropurpurea_, Link, Fil. Hort. Berol., p. 59.—Fée, Gen. Fil., p. 129.—Hooker, Sp. Fil., ii., p. 138.—Eaton, in Chapman’s Flora, p. 589; Gray’s Manual, ed. v., p. 660; Ferns of the South-West, p. 319.—Lawson, in Canad. Naturalist, i., p. 272.—Hooker & Baker, Syn. Fil., p. 147.—Fournier, Pl. Mex., Crypt., p. 119.—Williamson, Ferns of Kentucky, p. 52, t. 12. _Pteris atropurpurea_, Linnæus, Sp. Pl., p. 1534.—Michaux, Fl. Bor.-Am., ii., p. 261.—Swartz, Syn. Fil., p. 106.—Schkuhr, Krypt. Gew., p. 93, t. 101.—Willdenow, Sp. Pl., v., p. 375.—Pursh, Fl. Am. Sept., ii., p. 668. _Platyloma atropurpureum_, J. Smith.—Torrey, Fl. New York, ii., p. 488. _Allosorus atropurpureus_, Kunze, in Sill. Journ., July, 1848, p. 86; Linnæa, xxiii., p. 218.—Gray, Manual, ed. ii., p. 591.—Mettenius, Fil. Hort. Lips., p. 44. _Pellæa mucronata_, Fée, 9me Mém., p. 8. _Pellæa glabella_, Mettenius & Kuhn, in Linnæa, xxxvi., p. 87. _Pteris spiculata_, Schkuhr, Krypt. Gew., p. 92, t. 100.