Big Horn Mountains, Hayden. Thallus (in the specimens before me) of sub- tartareous, smallish, wart-like, ash-coloured areole (often quite resembling those of L. petrae) which are mostly crowded into an irregular crust. Apothecia from the hypothallus; smallish; about equaling the areoles; flattish; the obtuse margin becoming at length thin, and a little flex- uous; the black, naked disk, which is white within, resting on a black hypothecium. Spores 1-2; large; becoming brown, and at length blackish; oblong-ellipsoid and oblong; somewhat constricted-septate at the middle; becoming tetrablastish, and, at length, by repeated subdivision of the protoplasm, mural-polyblastish. Roundish spores also occur. This species occurs in a very constantly monosporous state (I have observed no other condition in the Western specimens, but New England one, their spore-sacks varying from 1- to 2-spored) and this state was separated by Flotow under the name of L. Mon- tagnei, adopted as a species by several writers; but Nylander, pro- bably quite rightly unites both conditions in his L. geminata, an arrangement anticipating the emended Rhizocarpon Montagnei (which also includes both forms) of the later work of Koerber (Parerg.p.229) I have possessed specimens from collected and have found it The lichen is now first-published as North American; but long collected Vermont, by W. Frost; and much distributed by myself, in Western Massachusetts. Endocarpon pusillum, Hedw. St. Crypt. / Fr. Lichenogr. p. 411, a. Schær. Enum. p. 234, a; & Lich. Helv. n. 115. Endopyrenium, Koerb. Syst. p. 323. Endocarpon Hedwigii, Ach. & E. hepatic- um, Ach. Lichenogr. p. 298. Nyl. Prodr. p. 176; Lich. Par. p. 80; Pyrenae. p. 15. Dermatocarpon, Th. Fr. Lich. Arct. p. 255. On the earth. Deer Creek, North Platte; and on the Snake fork of the Columbia, alt. 6000ft, Hayden.