272 FRYE 



i cell thick, wanting in Racelopus; marginal cells often of a different 

 form from the others. Vein one, extending at least nearly to the tip. 

 Inflorescence nearly always dioicous; sex organs terminal; antheridia 

 in a rather large cup or disk through which the plant generally again 

 grows. 



Calyptra narrow, often covered with a dense mat of branched 

 hairs which are directed away from the point and end freely; if not 

 with densely matted hairs, the apex of the calyptra is spinulose, or 

 has few to many hairs, or is quite smooth. 



Capsule large, cylindric, or prismatic with 2 6 angles. Peri- 

 stome present (except in Lyellia, Bartramiopsis and some species of 

 Psilopilum), single; teeth 32 or 64, rarely 16, unbarred, ligulate, tri- 

 angular in cross section. Columella expanded at the apex into a 

 shield-shaped membrane (epiphragm) covering the mouth of the cap- 

 sule and uniting with the tips of the teeth. Lid present. Pedicel 

 long, smooth (except in Racelopus). Spores .008 .021 mm., rarely 

 larger, smooth or nearly so. 



Total number of genera, 10; number.represented in western North 

 America, 7. Total number species, about 320; number in western 

 North America, 27. 



SYNOPSIS AND COMPARISON OF THE WORLD'S GENERA OF POLYTRI- 



CHACE^E. 



i. Calyptra with few or no hairs. 

 2. Lamellae on upper side 18 or fewer. 

 3. Lamina of i layer of cells. 

 4. Leaves bordered. 

 5. Peristome present. 

 6. Stomates wanting on capsules. 

 7. Capsule terete Catharinea. 



4. Leaves not bordered. 



5. Peristome present; calyptra with few hairs; lamellae on 



vein at back of leaves in nearly all cases. 

 6. Stomates present on capsule. 



7. Capsule terete Oligotrichum. 



5. Peristome wanting; or if present, calyptra without hairs ; 



without lamellae on back of leaves. 

 6. Stomates present on capsule. 



7. Capsule somewhat flattened, elliptical in cross section. 



Psilopilum. 



3. Lamina composed of 2 layers of cells. 

 4. Leaves not bordered. 



