OF WESTERN PENNSYLVANIA. 55 



base or often united above, or irregularly cleft, deep castane- 

 ous, articulate; exothecial cells yellowish-incrassate, irregular- 

 ly oblong to rectangular, the 4 or 5 uppermost rows much 

 smaller, rounded and obscure; calyptra cucullate, covering 

 about one-half of the capsule ; spores yellowish, smooth, about 

 .015-018 mm., maturing in late fall or winter. 



Usually on sandy soil in hilly or mountainous districts. In 

 Europe, and in North America, from Maine to Missouri and 

 North Carolina. Not common in our region. 



Allegheny: Powers Run, September 14, 1905. (Figured). 

 O. E. J. and G. E. K. ; Wildwood Road, March 

 29, 1908. O. E. J. and G. K. J. ; Thornhill, De- 

 cember 29, 1908. O. E. J. 

 McKean : West Branch, September 6, 1896. D. A. B. 



2. Ditrichum tortile [Schrader] Brockmueller. 

 (Plate VI) 



Cespitose, yellowish-green, rather dull : stems short, about 

 5-10 mm. high, erect or erect-ascending from a radiculose 

 base, mostly simple, reddish; leaves about 2.5-3.5 mm. long, 

 closely appressed-erect to somewhat spreading, usually some- 

 what secund or twisted, gradually lance-subulate and canalicu- 

 late from an ovate-lanceolate concave base, margins more or 

 less narrowly revolute, apex usually denticulate; costa strong, 

 less distinct at base, in the upper portion constituting about 

 one-third to one-half of the leaf-width, percurrent to slightly 

 excurrent; basal cells rectangular to linear-rectangular, alar 

 not different, rather thin-walled and hyaline, smooth, median 

 smaller, mostly about 2:1, rectangular to quadrate, smooth, the 

 apical sometimes bi-stratose ; perichaetial leaves more or less 

 sheathing, otherwise similar to the stem-leaves : seta reddish- 

 brown, shining, somewhat sinistrorse, erect, about 1 cm. long; 

 capsule oblong to oblong-cylindric, reddish to pale brown, 

 smooth, non-sulcate, not constricted below the mouth, abrupt- 

 ly narrowed to the seta at base, the urn about 1 mm. long; 

 aunulus uni-seriate; peristome single, rather low, reddish, the 

 16 teeth cleft into linear-subulate, distinctly trabeculate, some- 

 what spirally twisted divisions, at base united into a very low 

 membrane; operculum conic-rostellate, usually more or less 

 oblique; calyptra cucullate, pale; spores rather thin-walled, 

 smooth, yellowish-pellucid, about .015-018 mm., mature in 

 late fall or in winter : dioicous. 



Not uncommon on clayey soil in fields, along roadsides, 

 etc., in Europe, Asia, northern Africa, and in the eastern half 

 of North America from Labrador to the Gulf States. Not very 

 common in our region. 



Allegheny : On wet clay in old quarry, Library P. O., April 

 8, 1906, on dry rocky hillside. Powers Run, 



