316 A MANUAL OF MOSSES 



bordered above by a few small quadrate, sub-opaque, often 

 transversely elongated cells ; branch-leaves similar to the 

 stem-leaves, sometimes a little larger ; costa very short and 

 double or none; pericheetial leaves erect, the inner plicate and 

 gradually narrowed to a very slender serrate point, with a 

 very short and double costa or none : seta about 5-7 mm. long, 

 sinistrorse above, lustrous, castaneous ; capsule cylindric to 

 lance-oblong, the urn about 1-1.5 mm. long, erect to somewhat 

 inclined, symmetric; annulus none; exothecial cells somewhat 

 collenchymatous, brownish, oblong-rectangular, the upper 3 

 or 4 rows rounded-quadrate; peristome-teeth yellowish, lance- 

 subulate, finely cross-striolate, strongly trabeculate, the dorsal 

 lamellae projecting to form a rather conspicuous hyaline 

 border; segments about three-fourths as long, slender, cari- 

 nately split between the articulations, the basal membrane 

 about one-third as high as the teeth, cilia none or very rudi- 

 mentary; lid conic and w r ith a slender oblique rostrum about 

 one-half as long as the urn; spores in late fall to early spring, 

 about .014-.018 mm., smoothish, brownish, rather thinly in- 

 crassate. 



On rotten logs and on rocks in dark woods ; Labrador 

 and Newfoundland south, mainly in the mountains, to Georgia. 

 Rather uncommon in our region. 



Allegheny : \\ildwood Road Hollow, side of ravine 



under dense shade of hemlocks, November 



19, 1908. O. E. J. 

 Fayette : On rock in shaded woods in valley of 



Meadow Run, four miles south of Ohio 



Pyle, September 1-3, 1906. O. E. T- and 



G. K. J. 

 Westmoreland : "Shades," near Blackburn, March 25, 1910. 



O. E. J. and G. K. J. (Figured). 



18. ISOPTERYGIUM Mitten. 



Autoicous or dioicous : mostly slender to very slender, 

 cespitose, soft, mostly bright or yellow r ish-green : stem creeping 

 to ascending, upright only in the thick mats, mostly irregularly 

 branched; leaves uniform, obliquely inserted, smooth, usually 

 more or less two-seriate, from a narrow and little or not at 

 all decurrent base oval to oblong-oval and short-pointed or else 

 ovate to lance-oblong and acute to piliferous, margins plane 

 and entire to serrate; costa double, very short, or none; cells 

 prosenchymatous, smooth or papillose in the upper angle, the 

 basal shorter, the alar not usually differentiated : seta long, 

 smooth, mostly drying twisted ; capsule sub-erect to cernuous 

 or horizontal, with a collum, oval to oblong or cylindric, al- 

 most symmetric or weakly gibbous, when dry only rarely 

 arcuate and narrowed below the mouth, mostly smooth ; 



