252 American Midland Naturalist Monograph No. 6 



reaching 10 cm in length, prostrate or ascending, closely regularly pinnate, 

 plumose; leaves densely imbricated, falcate-secund to circinate, stem-leaves 1.8- 

 2.5 mm long, when dry usually plicate, and, especially towards the points, 

 more or less undulate and crisped, from a cordate-acuminate, plane-margined, 

 auriculate base rather abruptly and slenderly long-acuminate, plane-margined, 

 strongly serrate, especially at the base, somewhat decurrent; costa very short 

 and double or none; median leaf -cells about 8-15:1, the corners somewhat pro- 

 jecting dorsally, gradually towards the angles becoming irregularly quadrate- 

 hexagonal, shorter and wider, pellucid, forming poorly defined auricles of 

 about the same color as the rest of the leaf; branch-leaves considerably smaller 

 and narrower, not cordate-auriculate; perichaetial leaves slenderly lance-acumi- 

 nate; paraphyllia ovate, mostly at the base of the branches: seta brownish, 

 flexuous, slender, about 1.0-2.5 cm long, castaneous; capsule-urn about 2.5 mm 

 long, oblong to oval, slightly curved to almost straight, from the curved apex 

 of the seta mostly horizontal, not constricted below the mouth when dry; lid 

 conic-acuminate; annulus broad; peristome normally hypnoid, teeth yellowish, 

 segments carinately cleft, about as long as teeth, the cilia 2 or 3, stout, about 

 as long as the segments, the basal membrane about one-half the height of the 

 peristome; calyptra somewhat hairy when young; spores mature in summer, 

 smooth, yellowish-incrassate, about .01 5-. 018 mm. 



On moist, shaded earth and rocks, or bases of trees, in woods, more partic- 

 ularly in hilly or mountainous districts; Europe, Asia, northern Africa, and 

 from Newfoundland to the Rocky Mountains and south to Georgia and 

 Oklahoma. 



Armstrong Co.: Crooked Creek, one mi. s.w. of Tunnelton. C.M.B. Aug. 18, 

 1935. Beaver Co.: On ground. Raccoon Creek, 2 mi. w. of Little Traverse Creek. 

 C.M.B. Sept. 15, 1935. Blair Co.: A. P. Garber. (Porter's Catalogue). Butler Co.: 

 On wet roadside bank, Semiconon Run, 2]/2 mi. w. of Conoquenessing. Sidney K. East- 

 wood. March 24, 1935. Cambria Co.: Cresson. T. C. Porter. (Porter's Catalogue). 

 Elk Co.: McMinn. (Porter's Catalogue). McKean Co.: On rich, shaded bank of 

 stream, Langmade, April 3, 1897, and April 25, 1897 (figured), and on rocks bordering 

 rivulets, head of Gates' Hollow, Bradford, October 27, 1895. D.A.B. Washington 

 Co.: Linn and Simonton. (Porter's Catalogue). 



14. Rhytidiadelphus (Lindberg) Warnstorf 



Dioicous: more or less robust, stiff, loosely cespitose forming loose, wide, 

 stiff, green to yellowish or grayish, and rather lustrous mats; stem angled, long, 

 without rhizoids, simple to regularly or irregularly pinnate; branches partly 

 short and obtuse, partly long and acuminate, and often curved above; upper 

 half of the leaf spreading-squarrose to reflexed-squarrose, sometimes circinate- 

 pecund, mostly plicate, scarcely decurrent, from an ovate or cordate base more 

 or less long-acuminate, plane-margined, rather sharply serrate; costa reaching 

 above mid-leaf, or short, double, or sometimes none; cells narrowly linear, 

 smooth, or the upper angle projecting dorsally as a tooth, the basal wider, 

 shorter, more or less incrassate and porose, colored, the alar mostly not differ- 

 entiated; seta 2-4 cm long, castaneous; capsule horizontal to pendent, from a 

 very short neck thickly oval, dorsally gibbous, when dry and empty plicate, 



