THE POLYTRICHACE^E OF WESTERN NORTH AMERICA 28 1 



Named after Selwyn.^ 



Plants dioicous. Stems more slender than in C. undiilata. 



Leaves undulate when moist, with transverse rows of teeth on the 

 back, broader in proportion than in C angiistata, subspatulate, gen- 

 erally obtuse, excavated at base. Margin bordered, serrate to mid- 

 dle or below. Lamellae 4 — 6,9—13 cells high. Vein vanishing in 

 apex, toothed at back. Cells .025 — .050 mm. 



Calyptra quite smooth. 



Capsule nearly erect or subarcuate, narrowly cylindrical, dark pur- 

 ple, shining, width to length about as 1:6 — 8. Teeth shorter than 

 in Cnndiilata. Lid shorter rostrate than in C. undiilata. — On 

 clayey soil and in crevices of rock. — Revelstoke, British Columbia; 

 Rogers Pass and Beaver Creek in Selkirk Mountains, British 

 Columbia; Lesser Slave Lake, Athabasca, Canada; Kootenai 

 County, Idaho. 



OLIGOTRICHUM Lam. & DC. 



Name derived from oligo = few, and tricho = hair; referring to 

 the almost naked calyptra. 



Plants dioicous. Stems simple, 1—3 cm. tall, with rhizoids at base. 



Leaves not undulate, i cell thick; upper leaves lanceolate to ligu- 

 late, when dry incurved-hooked and rarely crisped, when moist 

 patent to squarrose from an indistinct sheath-like base, usually with 

 lamellae on back toward apex; lamina on back not toothed (except 

 sometimes in 0. parallelum). Margin not bordered, sometimes 

 inflexed. Lamellae on upper side 3 — 13 (in our species), wavy from 

 side to side (except in O. parallelum) , with crenulate margins (except 

 in O. parallelum), composed of similar smooth cells. 



Calyptra with a few erect hairs, rarely smooth. 



Capsule erect or inclined, symmetric, terete, oval or ovate, usually 

 straight, smooth, with very large 2-celled stomates. Peristome pre- 

 sent; teeth 32 (at least in ours), usually equal, pale throughout. Lid 

 readily dropping off, thinly rostrate from a conic base. 



Number species in western North America, 3; total number spe- 

 cies, about 10. 



' Alfred Richard Cecil Selwyn, Director of the Canadian Geological Survey from 

 1869 to 1895; editor of the Geological and Natural History Survey of Canada, and a 

 large contributor to the same. 



