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L. longidens (Lindb.) Macoun is evidently the most widely distributed 
of the three, and is fairly common in the White Mountains, for the writer 
has specimens from Mts, Osceola, Tecumseh, Carrigain, and the Scaur at 
Waterville, besides frequently seeing it, though not collected. Macoun, in 
his Catalogue Part 7, 1902, announced the first American station from Nova 
Scotia, on wet rocks. Dr. Evans, in Rhodora, 1907, says that “it seems to 
attain its best development on rocks, but it also occurs on logs.” 
All the specimens hitherto collected by the writer have been on bark, or 
in one instance upon rotten wood. Warnstorf would be justified in character- 
izing it, like the original species of the group, as “ hemixerophyt.” 
About Waterville, N. H., it frequents yellow birch, either live or dead, 
particularly between 2500-3000 ft. alt., especially on the north and east sides 
of the trees, and it is fairly abundant along the trail up Mt. Osceola between 
these heights. Its usual companions are small sterile Dic 7 'annm, Plagiothe- 
cium, Radula, and little green slender crawling sterile Jameso 7 iielIa, just the 
same color as theZ. longidens. Its zone of best development on the tree is a 
few feet above the ground, at a convenient height for collecting, for it does 
not grow about the tree bases, like A 7 io?nodo 77 . With a little practice, a likely 
tree can be detected at a considerable distance. When it gets above the 
line of yellow birch, it takes to the balsam scrub. 
Dr. Farlow first reported it from New Hampshire, giving several stations, 
and Chocora specimens given the writer are also on yellow birch. All these 
White Mountain stations are more or less in the shade. The Waterville 
specimens from the Scaur, at 2300 ft. alt. were on rotten wood, on the 
ground, in the shade of a spruce. 
In color L. longidens is a rich dark green, about Hooker No. i, in the 
field it looks at first sight much like Sphenolobus exsectus, but is easily dis- 
tinguishable with the lens; besides S. exsectus does not, as a rule, climb 
trees, a very rotten log or a bank full of old wood suits it better. 
Kaalaas, in his De Dist. Hep. in Nrv., 1889, where it seems to be pretty 
common, quotes Lindberg’s long and excellent description from Arn. & 
Lindb. Muse. Asiae bor. p. 50. He further says of its habitat: “This 
species forms small, dense, dark green or brown-green tufts on moss-cov- 
ered, shady, but tolerably dry cliffs, and stones or granitic mountains, some- 
times, but more seldom it grows also on old tree-trunks, or on rotten stumps 
preferably of conifers, and then preferably grows in less dense tufts.” 
It is quite common in the hilly and lower parts of Norway, particularly 
in the southern and eastern regions, but grows neither on the coast nor on 
