58 American Midland Naturalist Monograph No. 6 



ranged in rows, in the upper part of the leaf about 6 or 8 rows on either side 

 of the costa, the apical cells larger and more hyaline, the basal cells pellucid 

 and elongate-rectangular, about 2-8:1: seta erect, 2-3 mm high, yellowish; 

 capsule erect, symmetric, oval; the urn wide-mouthed, about 0.5-0.7 mm high, 

 brownish, when dry and empty 16-striate; operculum about as long as urn, 

 obliquely rostrate from a broad base; peristome-teeth rather abruptly subulate 

 from, a broad base, small, not very persistent, articulate, papillose; spores about 

 .018.020 mm, minutely roughened, yellowish-pellucid, maturing in mid- 

 summer; calyptra cucullate, covering about two-thirds of the urn; exothecal cells 

 yellowish, incrassate, irregularly oblong to rectangular, the upper two to four 

 rows much smaller and rounded. 



In crevices in various kinds of rocks, in moist, shady cliffs, mountains 

 from Canada to North Carolina and Missouri. 



Fayette Co.: On sandstone rocks near Bear Run falls, Oct. 30, 1935. Adam M. 

 Barker. Lawrence Co.: Slippery Rock Creek. Wm. James. (Porter's Catalogue). Mc- 

 Kean Co.: Sandstone rocks between Hawkins and Rutherford hollows, March 12, 1894; 

 and Toad Hollow, July 19, 1896, and August 1, 1897. D.A.B. 



This moss occurs on the sandstone cliffs of Chestnut Ridge six miles south of the 

 Pennsylvania-West Virgmia state line. July 4, 1909. O.E.J. &i G.K.J, (figured). 



2. Rhabdoweisia denticulata var. Americana Culman 



Closely similar to the species but with the leaves narrower and narrowly 

 acute, entire or only slightly denticulate. 



We have seen no sp>ecimens of this variety from our region although Grout 

 reports it as occurring with the species and refers most of the collections to it. 



9. Oncophorus Bridel 



Autoicous: rather large, cespitose in broad, soft, bright green or yellowish- 

 f^reen tufts, usually radiculose below: stems thickly foliate; leaves when dry 

 crisped, when moist ascending to squarrose, from a sheathing base more or 

 less abruptly long-acummate or subulate, concave, carinate; costa strong, per- 

 current or excurrent; cells in the sheathing base of the leaf long-rectangular, 

 translucent to hyaline, the alar sometimes somewhat differentiated, the laminal 

 cells small, mostly rounded-quadrate, at the margin bi-stratose; perichsetial 

 leaves sheathing to above the middle, abruptly subulate: seta long, erect; cap- 

 sule unsymmetric, strumose with a short collum, when empty more or less 

 weakly sulcate; annulus indistinct; peristome-teeth 16, deeply inserted, approxi- 

 mate, united below into a tube which is adherent to the wall of the capsule, 

 the teeth 2- (3) -divided to the middle, outwardly minutely papillose in longi- 

 tudinal lines, the inner surface with 1 (or 2) delicate longitudinal lines and 

 strongly projecting transverse plates; operculum at least half as long as the 

 capsule, obliquely rostrate; calyptra cucullate. 



A genus of 5 species widely distributed on damp gravelly soil, on moist 

 non-calcareous rocks, or on decaying logs. Only one known species in our 

 range. 



