BAKNES — NORTH AMERICAN MOSSES. 297 



costa ending in apex or apiculus: margin narrowly revolute; cells ovate or 

 rotund above, chloi-ophyllose, walls thickened below (especially near nerve), 

 elongated, narrow walls irregularly thickened, papillae in upper part of 

 leaf salient, simple or furcate: inflorescence autoicous: capsule emergent, 

 <jvate, collum equaling it in length, defluent into seta, when dry slightly 

 constricted under mouth and sulcate, strise 8, indistinct; stomata immers- 

 ed; annulus simple; peristome double, teeth pale yellow, 8, when dry re- 

 flexed against wall of capsule apex truncate and fimbriate, remainder en- 

 tire, or rarely apex lacunose, papillae minute, distinct; cilia irregular, 8, 

 fugacious, sometimes fragmentary; spores 15-18jU. Bot. Centrabl. 44: 

 418. 1890. — Yellowstone National Park, Wyoming. 



227. Orthotrichum rhabdophorum Vent. — Densely pulvinate, dark 

 green: stems erect, somewhat branched, 1.5-2 cm. long, below tomentose 

 xadiculose: leaves when dry imbricate, when moist becoming suddenly re- 

 curved, then erect spreading, lanceolate, or lanceolate from an ovate base, 

 acuminate, margin strongly revolute nearly to apex; cells above rotundate, 

 walls thickened, papillae bi- or tri-furcate, salient; inflorescence autoicous: 

 perichffitial leaves for most part reaching middle of capsule, sometimes cap- 

 sule entirely exserted: capsule when dry and operculate ovate-cylindrical, 

 with faint reddish striae, when moist ovate-elongate, constricted below 

 mouth, collum short, passing abruptly into seta, old capsules sulcate at 

 least to middle; annulus double or triple; peristome simple or rarely double, 

 teeth 16, when dry recurved, sparsely papillose; cilia if present more or 

 less perfect, erect, spores B-H-14/(. Bot. Centrabl. 44: 418. 1890. — Oas- 

 •cades. Thorp, Washington. 



228. Orthotrichum arcticum Schpr. — Tufts dense, more or less de- 

 pressed, dark green or blackish, 1-2 cm. long; stems branched, rigid: leaves 

 densely imbricate when dry, when moist becoming recurved and then erect- 

 spreading, obovate or oval-lanceolate and more or less pointed, recurved at 

 margin and revolute in lower half; costa vanishing below apex in lower 

 leaves and almost at point in upper leaves; cells at base quadrangular, 

 smooth and with unequally thickened walls, passing gradually above into 

 relatively large rounded or subhexagonal cells with thick walls and pro- 

 vided with salient bi- or tri-furcate papilla: perichsetial leaves larger at base, 

 more or less acuminate and a little longer than others: inflorescence autoi- 

 cous: capsule emergent and sometimes exerted, oval or oval oblong, when 

 dry sub-urceolate and faintly furrowed; collum straight and abruptly con- 

 tracted; annulus triple; peristome double, teeth 8, bigeminate, split 

 to middle and more or less lacunose along the middle line, finely and 

 densely papillose, reflexed when dry; cilia often fragmentary, not passing 

 half height of teeth, of one or two rows of cells. Husnot, Muse. Gall. 

 172. — Greenland. 



228a. Orthotrichum Macounii Aust. — Autoicous: robust, in broad 



