The genus Desmatodon in North America . 
R. S. WILLIAMs 
(WITH PLATE IT) 
The work on this genus was mostly done some four or five years 
ago, but little has since occurred, so far as the author knows, to 
cause any important changes. Twelve species are here included 
in the genus as against thirteen in the Lesquereux & James Man- 
ual, but two of these thirteen species, D. neomexicanus and D. ner- 
vosus belong to Tortula while one other, D. arenaceus, is reduced 
to D. obtusifolius. This leaves ten of the Manual species, the two 
additions being D. Sprengelii, originally from Santo Domingo and 
discovered in Florida in 1916 by Dr. J. K. Small, and D. stomato- 
dontus from Jalisco, Mexico. 
Desmatodon Bushui Card. & Thér., from Missouri, belongs to 
Tortula, fide Brotherus; D. Sartorii (C. Mill.) Paris, from Mexico, 
is a Leptodontium; and D. systylioides Ren. & Card., from New- © 
foundland, a Pottia. 
DESMATODON Brid. Musc. Recent. Suppl. 4: 86. 1819 
Plaubelia Brid. Bryol. Univ. 1: 522. 1826. 
Trichostomum § Desmatodon C. Miill. Syn. 1: 588. 1849. 
Didymodon § Desmatodon Kindb. Eur. & N. Am. Bryin. 2: 273. 
1897. 
Dioicous or monoicous. Mostly alpine plants of medium or 
small size, usually growing in rather compact cushions on moist 
earth. Stems, mostly with central strand, simple or somewhat 
branching, closely leaved and more or less radiculose. Leaves 
erect-flexuous and appressed when dry; ovate and oblong to 
oblong-lanceolate or somewhat spatulate, concave, the margins 
flat, recurved or broadly incurved; entire or slightly serrulate in 
the upper part, sometimes colored or thickened, the apex mostly 
broadly acute, with costa vanishing below the apex, percurrent 
or excurrent into a short awn or elongate, nearly smooth hair- 
point. Costa in cross-section usually showing two or four guide- 
cells, one or two rows of large cells on the ventral side and on the 
dorsal side, a large stereid band, with outer cells more or less 
