96 A MANUAL OF MOSSES 



brane, two or three times clextrorsely twisted ; spores mature 

 in late spring or early summer. 



On rocks, usually calcareous, in hilly or mountainous dis- 

 tricts, Europe, Asia, northern Africa, and, in North America, 

 from Greenland to West Virginia and from Idaho to Van- 

 couver Island. Rare in our region. 



Cambria: Cresson. Jantcs. ( Porter's Catalogue ). 



2. Tortella humilis (Hedwig) New Combination. 



(Tortula caespitosa Hooker and Greville ; Barbuhi caespitosa 

 Schwaegrichen). 



(Plate XIII) 



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 perichretial leaves 

 similar and sheathing; costa strong, excurrent-cuspidate ; the 

 lower one-fourth of the leaf has a large V-shaped patch of hya- 

 line rectangular cells reaching about .018X-085 mm., the 

 median cells rounded-hexagonal, papillose, rather opaque, much 

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

 seta yellowish-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, 

 articulate 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. Rather 



common in our region. 



Allegheny : Coraopolis, September n, 190=;, and near 

 Carnot, October 11, 1908. O. E. J. (Figured). 



Cambria : James. (Porter's Catalogue). 



Fayette : Ohio Pyle, September 13, 1906. O. E. J. 

 and G.'K. J. 



Huntingdon : On limestone rocks, Pennsylvania Furnace, 

 July 13, 1909. O. E. J. 



McKean : Bolivar Run, September 6, 1897. D. A. P>. 



7. DIDYMODON Hedwig. 



Dioicous, rarely synoicons : paraphyses filiform : mostly 

 slender plants, red or brown, cespitose ; stem with central 



