84 American Midland Naturalist Monograph No. 6 



gin, above becoming abruptly smaller, chlorophyllose, rounded, incrassate, 

 papillose: seta 1-3 cm long, reddish below, paler above; capsule cylindric, 

 2.5-3.5 mm long, usually somewhat curved, almost erect; lid obliquely and 

 slenderly conic-rostrate, at least one-half as long as urn; peristome-teeth long 

 and from a low basal membrane, two or three times dextrorsely twisted; spores 

 mature in late spring or early summer. 



On rocks, usually calcareous, in hilly or mountainous districts, Europe, 

 Asia, northern Africa, and, in North America, from Greenland to the Gulf 

 and from Idaho to Vancouver Island. 



Apparently rare in our region. Cambria Co. : Cresson. James. (Porter's Catalogue). 



2. ToRTELLA HUMILIS (Hedwig) Jennings 

 (Tortula caespitosa Hooker and Greville; Barbula caespitosa Schwaegrichen ) 



Plate XVII 



Loosely cespitose, green to yellowish-green, about 5 mm high; leaves 

 crispate when dry, erect-spreading when moist, oblong-lanceolate and about 2 

 mm long below, the upper linear-lanceolate and up to 3.5 mm long, somewhat 

 concave, the margin plane or sometimes involute, the perichaetial leaves simi- 

 lar and sheathing; costa strong, excurrent-cuspidate; the lower one-fourth of 

 the leaf has a large V-shaped patch of hyaline rectangular cells reaching about 

 .018 X .085 mm, the median cells rounded-hexagonal, papillose, rather opaque, 

 much smaller, about .007-.008 mm in diameter, the upper similar: seta yel- 

 lowish-brown, 15-20 mm long, erect, dextrorse; capsule yellowish-brown; ovoid- 

 cylindric, about 2-2.5 mm long, 0.5 mm thick, erect, symmetric, sometimes 

 arcuate, tapering at the base; peristome single, of 32 filiform, papillose, articu- 

 late teeth about 0.6-0.8 mm long, two or three times dextrorse, arising from a 

 low membrane scarcely exserted above the mouth of the capsule; spores globose, 

 somewhat papillose, about .008-.011 mm, mature in early summer; operculum 

 narrowly conic-rostrate; calyptra smooth, cucullate, rostrate, covering about 

 one-half of the capsule. 



Almost cosmopolitan in temperate or sub-tropical regions on earth and on 

 the roots of trees in the woods. 



Allegheny Co.: Coraopolis, September 11, 1905, and near Carnot, October II, 

 1908. O.E.J.) (figured). Cambria Co.: James. (Porter's Catalogue). Fayette Co.: 

 Ohio Pyle, September 1-3, 1906. O.E.J, and G.K.J. Huntingdon Co.: On limestone 

 rocks, Pennsylvania Furnace, July 13, 1909. O.E.J. Lawrence Co.: On VanPort lime- 

 stone, Squaw Run, n. of EUwood City. C.M.B. Nov. 26, 1948. McKean Co.: Bolivar 

 Run, September 6, 1897. D.A.B. Somerset Co.: Vicinity of Trent. Aug., 1932. C. 

 M. Hepner. Washington Co.: At root of tree, Snake Woods near Washington. Nov., 

 1891. Linn & Simonton. Westmoreland Co.: Chestnut Ridge, s.e. of Torrance. 

 C.M.B. June 13, 1943. 



7. DiDYMODON Hedwig 



Dioicous, rarely synoicous; paraphyses filiform: mostly slender plants, red 

 or brown, cespitose: stem with central strand, thickly foliate, radiculose, the 

 branches reaching to about the same height; leaves more or less keeled, erect- 

 spreading, mostly lanceolate from a broad base, the margin revolute; costa 



