254 American Midland Naturalist Monograph No. 6 



auriculate at base, the insertion narrow and decurrent; leaves plicate, denticu- 

 late, papillose dorsally, gradually tapering above to a sub-acute apex; branch- 

 leaves narrower and smaller towards the ends of the attenuate branches; costa 

 forked, or of two parallel divisions reaching about three-fourths the length of 

 the leaf; perichaetial leaves non-costate, the acuminations squarrose; median 

 leaf-cells linear, about 8-10:1, at the angles oblong-hexagonal, pellucid, not 

 usually forming distinct auricles, the upper cells dorsally forming spinulose 

 papillae: seta 1.5-3.5 cm long, rather rigid, lustrous, castaneous; capsule turgid- 

 oblong, large, castaneous, about 3 mm long, dorsally gibbous, inclined or more 

 nearly horizontal by a curve in the upper part of the seta, when dry more or 

 less plicate and constricted below the mouth; the exothecial cells rounded- 

 hexagonal, rather small, incrassate, castaneous; lid conic, acute; annulus 2-3- 

 seriate; peristome normally hypnoid, the teeth orange-yellow, strongly trabecu- 

 late, dorsally lamellate, the lamellae papillose but non-striate, projecting to 

 form a distinct border; the segments carinately split, the cilia 2 (or 3) and 

 about as long as the segments, stout, the basal membrane reaching about one- 

 half the height of the peristome; spores medium-walled, smooth, yellowish, 

 .018-. 025 mm, ripening in winter or early spring. 



On shaded banks, humus, or rotten logs in cool woods with a moderate 

 amount of moisture, or in swamps; Europe, Asia, northern Africa, and, in 

 North America from the Arctic regions south to the northern United States, 

 and along the mountains in North Carolina, in ravines and cool, rocky woods. 



Cambria Co.: T. C. Porter. (Porter's Catalogue). Elk Co.: McMinn. (Porter's 

 Catalogue). McKean Co.: On decaying leaves under hemlocks, Marilla Brook, Brad- 

 ford, June 5, 1895 (figured), and September 29, 1894; Bennett Brook, July 15, 1893. 

 D.A.B. Washington Co.: Linn and Simonton. 



15. Rhytidium (Sullivant) Kindberg 



Dioicous: very robust, in wide, loose, yellowish or brownish-yellow tufts 

 or mats: when dry stiff and lustrous; stems long, tumid, with hooked tips, 

 prostrate to ascending or erect, with few or no rhizoids, simple to regularly 

 pinnate, or bipinnate, rarely bushy; branches 2-seriate, short and thick, or 

 longer, acuminate and downwardly arcuate; leaves crowded, imbricate, falcate- 

 secund, concave, plicate, rugose, scarcely decurrent, lance-ovate to oblong- 

 ovate, narrowed into a long, canaliculate, lance-subulate, sharply-toothed 

 point, the margin more or less revolute; costa simple, thin, reaching; to mid- 

 leaf; median leaf-cells narrowly vermicular, with dorsally (sometimes a few 

 ventrally, also) projecting and forward-pointing teeth-like papillae at the upper 

 end of the cell, towards the costa at base the cells more lax, rectangular, porose, 

 incrassate, the alar region not excavate, the alar cells forming a distinct longi- 

 tudinal band of small, quadrate and polygonal, yellowish, incrassate, numerous 

 cells; inner perichaetial leaves elongate-lanceolate, slenderly acuminate, plicate, 

 serrate, ecostate: seta 2-5 cm long, castaneous, when dry twisted; capsule in- 

 clined to horizontal, elliptic to sub-cylindric, dorsally gibbous, when dry arcu- 

 ate and constricted below the mouth, brownish; annulus 3-seriate, remaining 

 attached to the operculum; lid convex-conic, shortly and obliquely rostrate; 



