OF WESTERN" PENNSYLVANIA 93 



without a central strand, triangular in cross-section ; leaves 

 erect-spreading, rarely squarrose-recurved, when dry involute, 

 sometimes somewhat twisted when dry, not crisped, more or 

 less carinate. elongate-lanceolate, acuminate ; costa mostly 

 ending below the apex ; laminal leaf-cells thick-walled, smooth 

 or papillose : seta long, erect ; capsule erect, symmetric, obovate, 

 firm, when empty smooth and pyriform ; peristome none ; lid 

 obliquely long-rostrate from a broad base, remaining attached 

 to the columella and deciduous thus attached; calyptra cucul- 

 late. covering about half of the urn. 



A widely distributed genus of about 21 species, occurring 

 mainly on calcareous rocks ; 8 species in North America ; only 

 one occurring in our region. 



1. Hymenostylium curvirostre [Ehrhart] Lindberg. 



(Gymnostonmm cnrrirostre Hedwig; IVcisia currirostris Muel- 

 ler). 



(Plate XII) 



Closely cespitose. 2-4 cm. high, bright green above, 

 darker and more or less ferruginous below : leaves little or not 

 at all twisted when dry, erect to recurved-spreading when 

 moist, narrowly lanceolate-acuminate. 1-1.5 mm. long, apex 

 acute, base sub-clasping, margin entire but papillose, as are 

 also the entire upper and lower surfaces of the lamina and costa ; 

 costa strong, vanishing just below the apex, at base occupying 

 about one-eighth the entire width of the leaf; upper leaf-cells 

 rounded to sub-quadrangular, the lower towards the costa be- 

 coming elongate-rectangular: seta 8-10 mm. long, lustrous, 

 castaneous ; capsule about 1 mm. long, rounded ovate, lustrous, 

 castaneous, widest towards the mouth, when dry and empty 

 decidedly urceolate ; peristome none ; operculum with a long 

 and oblique rostrum at least two-thirds the length of the urn, 

 the operculum often remaining attached to the columella for 

 some time after the spores have been shed; spores yellowish, 

 moderately incrassate, smooth, about .014- .017 mm. in diame- 

 ter, mature in September or October. 



Not uncommon on wet cliffs, principally calcareous, in 

 Europe. Asia, northern Africa, and, in North America, from 

 Alaska to Labrador south to California and the Carolinas. 



Allegheny : Guyasuta Hollow, Aspinwall. on wet cliff 



near waterfalls, October 12 and 25, (Fig- 

 ured) 1908, and September 8, 1909. O. E. J. 



Lawrence : On wet face of exposure of the Homewood 



Sandstone, near Rock Point, October 15, 

 1910. O. E. J. and G. K. J. 



