Two new Species of Grimmia from Montana 



By R. S. Williams 



(With Plates 19, 20) 



Grimmia (Eugrimmia) Brittoniae 



Growing in dense hemispherical tufts up to 3.5 cm. high. 

 Stems slender, usually bearing long branches. Outer perichaetial 

 and upper stem leaves with blade 1 mm. in length, oblong, some- 

 what lanceolate pointed, concave, flat on the borders with nearly 

 smooth hair point up to 3 times the length of blade : lower leaves 

 a little smaller with hair point scarcely equaling blade, more con- 

 cave and somewhat recurved : inner perichaetial leaves minute, 

 triangular, with hair point 8 to 10 times the length of the blade : 

 upper cells irregular, roundish or quadratic, about .006 mm. in 

 diameter, gradually becoming elongated below, toward base 3 or 4 

 times longer than broad near costa and 1 ]/ 2 to 2 times longer than 

 broad near margin : cells but slightly sinuous walled when filled 

 with chlorophyl, later on the walls becoming distinctly sinuous 

 both above and below: sections of costa show two large cells on ven- 

 tral side with usually 5 or 6 surrounding cells, in single row, on 

 dorsal side : leaf lamina is of a single row of cells with sometimes 

 a doubling of one row in one or both margins : apparently dioi- 

 cous : fruit unknown. 



Growing on shaded perpendicular walls, partly calcareous, in 

 rather dry places. Collected for several seasons in Bad Rock 



Mont 



M r s 



all students and lovers of our mosses will ever be indebted. 



Grimmia (Eugrimmia ?) tenuicaulis 



In compact tufts up to 6 cm. high. Stems very slender, often 

 thread-like, with few simple, mostly short branches : perichaetial 

 and upper stem leaves rather broadly ovate-lanceolate, concave, 

 revolute on borders, blade 1 ^ mm. long, with rough hair point 

 about y^ blade in length, the papillae of point spreading, often re- 

 curved : moistened leaves erect-spreading : upper cells irregular, 

 somewhat transversely or vertically elongated, mingled with 

 rounded cells .004-.006 mm. in diameter : cells toward base 

 more or less elongated rectangular, those near margin from nearly 



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