-83- 



Lindb. and Stereodon revolutus Mitt, belong to the same species. 5. revo- 

 lutus, Fig. 3, has the leaves with broadly re volute margins, the cross-section 

 of stem with small outer cells, etc. S, piicatulus. Figs, i, 2 and 4, on the 

 contrary, has the leaves broadly triangular with long acumen and plane 

 margins the outer cells of the cross section of stem are much larger, etc. 

 5. plicatulus Lindb. is thus very different from 5. revolutus Mitt, and is 

 much nearer related to 5. callichroum Brid., Fig. 5, and in my opinion a very 

 good species, which thus not only is found in Siberia and East Russia, but 

 also in North America. Helsingfors, Finland, May 21, 1903. 



THE MOSSES OF ALASKA. ^ 



By J. Cardot and I. Theriot 

 From " Papers from the Harriman Alaska Expedition." 

 (Concluded.) 

 PoLYTRiCHUM YuKONENsE Card, and Ther. 



Stem 5-8 cm. high, simple or sparingly branched, denuded of leaves for 

 a long distance, covered at base with a white tomentum. Leaves rigid, sub- 

 erect when dry, erect-spreading when moist, 4-6 mm. long, 8 broad, 

 appressed from a subsheathing yellowish base, shortly linear-acuminate, 

 tapering into an entire fuscous tip, erect entire margins, lamellae about thirty, 

 crenulate on margin, composed of eight to twelve cells in transverse section, 

 the apical cell larger and deeply emarginate. Other characters unknown. 

 From Yukon River (W. H. Dall, in 1867). 



This species is easily distinguished from the smaller forms of P. com- 

 mu7ie by its short and entire leaves, its higher lamellae with more deeply 

 crenated borders and more strongly emarginated marginal cells. 



A recently described species, P. Jetisenii Hagen {P .fragilifoliu77i Lindb. 

 fil. mss.), which has been found in Greenland, Spitzbergen, Lapland and 

 Wyoming, comes very near our P. Yukonense by its size and the height and 

 structure of its lamellae, but differs from it by its leaves being longer and 

 dentate at the point, by the cells of the basilar and subvaginant part, which 

 are wider, and by the much less emarginated apical cells of the lamellae. 

 Brachythecium Beringianum Card, and Ther. 



Densely caespitose, resembling in habit small forms of B. albicans. 

 Stem erect, 3-4 cm. high, much branched, branches erect, sometimes fasti- 

 giate, julaceous. acute. Leaves crowded, imbricate, the stem leaves 1.5 mm. 

 long, 0.8 broad, ovate-lanceolate, from a slightly decurrent base, quite 

 abruptly and short-acuminate, concave, plicate, with entire margins, plane 

 or refiexed, the branch leaves smaller, longer acuminate, costa thin, 30-35// 

 broad at base, extending barely to the middle, often forked and sometimes 

 very short; alar cells numerous, quadrate, elongated in the five to six 

 rows next to the margin, the rest linear, 40-45// long, 6-7 broad. Walls 

 incrassate. Other characters unknown. 



From St. Paul Island (Trelease, 1861, 2087); Agattu Island (U. S. S. 

 Albatross Exped., 40). 



\ 



