CoKEeR: NortH AMERICAN SPECIES OF ENCALYPTA 437 
rostrate; peristome originating at or below the mouth; simple 
(haplolepideous) or compound (diplolepideous), sometimes lacking; 
preperistome sometimes present; annulus simple or compound; 
teeth varying in length, usually papillose or striate, entire or 
split along the median line, rarely more or less united and attached 
to the endostome by a hyaline membrane, sometimes nodose or 
with short intermediate cilia; walls of the urn (theca) either smooth 
or striate, striae sometimes visible only after sporosis, sometimes 
spirally twisted or deeply grooved; neck (column) short, stoma- 
tose, or the stomata scattered along the wall; spores smooth or 
rough, usually maturing in spring or summer, variable in size. 
Type species, Bryum extinctorium L. 
The genus divides itself naturally into two groups or sections: 
§ 1. Haplolepideae, with the peristome single or absent, and § 2. 
Diplolepideae, with the peristome double and variable. 
In §1 are included 4 species that are found in Europe and 
North America: E. alpina, E. extinctoria, E. laciniata, and E. 
rhabdocarpa, the last two approaching the Diplolepideae by having 
a preperistome. 
In § 2 are included 4 species, also common to Europe and 
North America: E. apophysata, E. brevicolla, E. procera, and 
E. contorta; of these E. contorta has not yet been found fruiting 
on this continent. : 
Key to species 
§1. HapLoLePmear. Peristome simple or lacking; teeth, when 
present, short, lanceolate; capsule not twisted. 
Capsule striate, or becoming so when old. 
Calyptra lacerate at base, nearly smooth at apex. 
Peristome only occasionally found. Walls of cells 
at base of leaves thickened. 1. E. exiinctoria. 
Peristome usually present, often with preperistome. 
alls of cells at base of leaves not thickened. 2. E. rhabdocarpa. 
Capsule smooth. 
Calyptra lacerate at base but not fringed. Peristome 
never present, spores papillose. 
Calyptra with a persistent or fugacious fringe of larger 
cells. Peristome usually present, deeply inserted. . E. laciniata. 
§ 2. DreLoLeripear. Peristome double, teeth usually long and 
slender; ostome more or less adherent to the teeth. 
3. E. alpina. 
of leaves with short walls papillose. 5. E. apophysata. 
