138 American Midland Naturalist Monograph No. 6 



cells angular, hexagonal to quadrate, non-collenchymatous : seta solitary, red; 

 capsule elliptic-oblong, abruptly contracted into the neck, straight and more or 

 less horizontal, brownish; operculum shortly rostrate: dioicous, antheridial 

 flower discoid. Mature in late summer. 



On moist rocks, usually calcareous, along cool shaded ravines and streams: 

 Europe, Asia, North America from Greenland to British Columbia and south 

 through the northern part of the United States to North Carolina. 

 One report in our region. Blair Co.: Porter. (Porter's Catalogue). 



3. Mnium serratum Schrader, Schwaegrichen 



(M. marginatum Beauvois; Astrophyllum marginatum Lindberg) 



Plate XXV 



Loosely cespitose in soft tufts, rather dark green: stems and lower leaves 

 often deep reddish tinged, stems slender, rather short, usually 1.5-3 cm in our 

 spcimens, simple or branched below with erect branches; leaves rather remote, 

 strongly decurrent, the lower ovate-lanceolate, the upper oblong spatulate- 

 lanceolate, all acuminate, the strong red border sharply doubly serrate, the 

 leaves when dry more or less twisted but hardly crispate; costa in upper leaves 

 confluent with the border in the apiculus but in the middle and lower leaves 

 and often even the upper leaves of sterile shoots the costa ends below the apex, 

 not spinose; leaf-cells from .020-.035 mm in diameter, irregularly rounded, 

 somewhat incrassate, strongly collenchymatous, the basal elongate: seta mostly 

 single; capsule horizontal, yellowish to brown, oval-oblong, tapering at neck; 

 peristome yellow or sometimes brown, inserted, the teeth lance-linear, pellucid 

 yellowish-brown, papillose above, strongly trabeculate, divisural faint; segments 

 a little shorter than teeth, papillose above, slender, cilia 3 (2), the basal mem- 

 brane reaching somewhat above the middle; spores rounded, about .025-.030 

 mm; operculum stoutly short- rostrate; synoicous; mature in spring. 



Usually near streams on shaded banks or rocks, or in crevices of rocks 



where moist, in Europe, northern Asia, and, in North America, from Anticosti 



to Alaska and south to Tennessee, Missouri, and the Southwest. 



Now known from the following counties: Allegheny, Armstrong, Butler, Elk, Fayette, 

 McKean, Somerset, Washington, and Westmoreland. Specimen figured: Hawkins and 

 Quintuple, McKean Co. D.A.B. Aug. 2, 1895. 



4. Mnium spinulosum Bryologia Europaea 

 Plate LXV 

 Tufted, erect, 1-1.5 cm tall, drying a bright emerald green; stems reddish 

 and radiculose below; similar in many respects to Mnium serratum,, the lower 

 leaves small and scale-like, the middle and upper abruptly larger, elliptic to 

 obovate or spatulate at the apex of the stem, decurrent, acute, sharply doubly 

 serrate on the thickened reddish border in the upper two-thirds, not crisped 

 when dry; costa strong, sometimes reddish, percurrent, not dorsally toothed, 

 often ending below the apex in the lower and middle leaves; leaf-cells about 

 .020-. 030 mm, angled hexagonal, or below rectangular, incrassate, non-collen- 

 chymatous: synoicous: sporophytes single (or clustered), seta erect, usually 

 reddish yellow, 1.5 to 2 cm high, abruptly hooked at the top and abruptly 



