Par? 2, 1913] DICRANACEAE 105 
lower leaf-cells much elongate, the upper ones short, often quadratic; cell-walls more or less 
thickened and pitted and flat or mamillose on both sides, with often furrows between the rows 
of cells; alar cells distinct ; inner perichaetial leaves with a highly convolute base narrowed to 
a slender point often extending to or above the capsule. Seta erect, smooth, mostly solitary. 
Capsule erect, narrowly ovate to cylindric, smooth, with stomata in 1 or 2 rows near the 
base; peristome inserted well below the mouth, of mostly narrowly lanceolate, reddish, very 
papillose, not striate teeth, undivided or more or less divided along the median line; lid conic, 
beaked. Spores small, 16 u or less in diameter, not quite smooth. Calyptra smooth above, 
entire at the base. 
Type species, Trichostomum vaginatum Hook. 
Leaves without a hair-point; costa 40-100 u wide below. 
iA Leaves narrowed from a distinctly broadened base to a lanceolate point, 
usually crispate when dry. 
Stem-leaves more or less Spreading from their insertion; leaf-base either 
narrowly ovate or ovate-lanceolate and about 3 mm. long, or the 
leaves gradually narrowed from near the base to the apex. 
Alar cells forming a distinct, reddish or hyaline, nearly square group, 
about 200 high, with some longer, narrower cells intervening 
between the alar ones and the costa. 1. H. flexuosum, 
Alar cells forming a rather ill-defined band, brown to nearly hyaline, 
extending upward scarcely 100 4 and from the margin to the costa. 2. H. terebellatum. 
Stem-leaves with a broadly ovate or obovate, mostly erect, imbricate 
base, usually 2 mm. or less long, distinctly and often abruptly 
narrowed to a spreading lanceolate point. 
Leaves with cells nearly or quite flat on both sides and without fur- 
rows between the rows; border or Sometimies the upper part of the 
hlade of a double thickness of cells: 3. H. calycinum. 
Leaves with cells on both sides more or less mamillose and with fur- 
rows between the rows. a 
Uppér leaf-margin of a double thickness of cells; median cells 
about 5 yu by 5-8 pz. 4. H. marginatum. 
Upper leaf-margin of a single thickness of cells; median cells E 
about 8u by 8-10 4. 5. H. arboreum. 
Ds Leaves linear or lingulate, the upper half about as wide, sometimes wider, 
than the basal part, never crispate. , 
Leaves 3.5 to 4.5 mm.”Tong, broadly lanceolate-pointed, with marginal 
teeth extending down one third to one half way toward the base. 6. H. Wrightii. 
Leaves 2 to 3 mm. long, with a few coarse marginal teeth at the abruptly : 
rounded apex and a stout apiculus formed by the excurrent costa. 7. H. Maxoni. , 
Leaves with a pale to hyaline, smooth hair-point; costa below about 354 wide. 8. H. piliferum. 
1. Holomitrium flexuosum Mitt. Jour. Linn. Soc. 12: 57. 1869. 
Antheridial flowers not known: plants in loose tufts with stout, slightly branching stems, 
brown and tomentose below, greenish-brown above, up to 8 cm. high: stem-leaves mostly 
9-10 mm. long, from an oblong-lanceolate, somewhat spreading base, gradually narrowed to 
a slender, lanceolate, serrulate point, very crispate or spirally twisted when dry and 1-1.5 
times as long as the base; costa shortly excurrent, dentate on the back about one third down, 
100 « wide a little above the base, in cross-section near the middle showing 5 or 6 guide-cells, 
wtih stereid-bands ‘above and below and outer cells differentiated mostly on the lower side 
onlv; cells throughout the leaf above the alar ones mostly elongate with thickened, pitted walls, 
except the marginal rows; median cells toward the costa 4-6 » wide and up to 20 » long; alar 
cells from dark reddish-brown to nearly hyaline, forming an almost square group extending 
upward about 200 and two thirds of the way to the costa; fruit not seen; (according to 
Mitten) with perichaetial leaves long-convolute, at apex narrow, extending one half way up 
the yellow, very slender seta: capsule cylindric, with peristome-teeth red, narrow, elongate, 
and entire. 
Type LocaLity: Andes near Quito, on branches at 2100 meters. . : 
DistRIBUTION: Known from our region only by a fragment collected in Mexico by F. Mueller. 
2. Holomitrium terebellatum C. Miill.; Ren. & Card. Bull. Soc. 
Bot. Belg. 31°: 151. 1893. 
“Monoicous’”’: stems flexuous, more or less branching, greenish-brown above, covered 
with reddish-brown tomentum below, 5-15 cm. long: stem-leaves mostly 9-10 mm. long, 
from an oblong-lanceolate, more or less spreading base, very gradually narrowed to a rather 
