(95 ) 
as well by the determination of some minute forms which have so far 
escaped attention, at the north, as by the addition of some most interest- 
ing ones, known to occur in Mexico, to our southern Flora. Adding these 
last indeed, the North American list which follows, would embrace not 
far from two thirds of the best settled types of Leptogium. 
Sect. 1.— POLYSCHIDIUM. 
1. LZ. intricatuliom, Nyl. Syn. p. 135. Beech trunks in the White 
Mountains (Herb. Oakes). Apothecia unknown; but the plant appears 
to be associable with the next. Collogonidia finally occurring in strings 
of three or four. 2. L. dendriscum, Nyl. Syn. p. 135. Branches of 
shrubs, Florida (Herb. E. Michener). Agrees generally with the lichen 
found in the island of Cuba (Mr. Wright) but the specimen is without 
fruit. ——3. L. muscicola (Sw.) Fr. Rocks, among mosses, in mountain- 
ous and alpine districts. White Mountains. Brattleborough, Vermont 
(Mr. Frost). Coast of California, and in the Yo Semite valley (Mr. 
Bolander). Islands of Behring’s Straits (Mr. Wright). 
Sect. 2.—LATHAGRIUM. 
4. L. albociliatum, Desmaz., Nyl. Lich. Scand. p. 35. Polyschidiun 
cetrarioides, Anz. Catal. Sondr. p. 7, & Lich. Langobard.n. 13. LD. leu- 
cothrix, Tuck. in litt. Rocks, among mosses, Mendocino county, and in 
the Yo Semite valley, California, (Mr. Bolander.) The regular, appressed 
fronds, one and a half to two inchesin diameter, are not well comparable 
with the reduced, muscicoline condition described and published by Anzi; 
but the agreement of the two plants in anatomical structure, as in all 
observed, essential features, is perfect. Apothecia of the European lichen 
not seen; those of the American are very commonly more or less ciliate, 
like the thallus; especially when young. Though growing here, as in 
Europe, in society with L. muscicola, the species has little enough, in 
either form, to associate it with that plant, beside its oblong-ellipsoid, or 
cymbiform, bilocular spores. As compared with the only published 
measurement of the foreign lichen (Anz. J. c.) the spores of ours are 
rather larger; measuring +?mmm.——We have found the distinction 
of a section Lathagrium (Synechoblastus, Auct.) sufficiently difficult in 
Collema; itis interesting however that the spore-anomaly upon which 
the distinction turns, recurs in Leptogium. LL. Brebissonii, Mont. (Syn- 
echoblastus ruginosus, Hepp) with ‘ fusiform-acicular, 8-12-locular’ spores, 
though an inhabitant of Europe, of the Canary Islands, and of Tahiti, is 
unknown as North American; but L. adpressum, Nyl. (Syn. p. 131) with 
fusiform, plurilocular spores, is a Mexican lichen (Orizaba, F. Miiller in 
Nyl. l.¢. Dr. Mohr !). 
Sect. 3.—EULEPTOGIUM. 
5. L. subtile, Nyl. On the earth. New England (C. Wright, H. 
