WILLIAMS: THE GENUS DESMATODON 213 
5. DESMATODON OBTUSIFOLIUS (Schwaegr.) Jur. Laubm. Oesterr. 
Ung. 135. 1882 
Barbula obtusifolia Schwaegr. Suppl. 1: 129. I8ITI. 
Desmatodon oblongifolius Hook. in Drummond, Musci Am. 174. 
1828 (nomen nudum). 
Toriula obtustfolia Schleich.; Broth. in E. & P. Nat. Pfl. 1°: 430. 
1902. 
Desmatodon arenaceus Sull. in Gray, Man. ed. 2,628. 1856. 
Desmatodon ohioense Schimp. Syn. 159. 1860. 
Desmatodon subtorquescens C. Miill. & Kindb.; Macoun, Cat. Can, 
Pl.6: 48. 1892 (apparently). 
Didymodon arenaceus Kindb. Eur. & N. Am. Bryin. 277. 1897. 
Apparently dioicous, the male plant much like the fertile but 
the terminal flower forming a more distinct rosette, the perigonial 
leaves scarcely differentiated, enclosing ten to twelve oblong an- 
theridia 0.2 mm. long with nearly filiform, slightly longer para- 
physes (the European plants are said to become autoicous by the 
older male stems finally bearing archegonial flowers, a condition 
not observed in North American specimens): plants in compact 
cushions, 3-4 mm. to 1 cm. high, with stems more or less branch- 
ing and radiculose at the base; leaves of lower stem very small, 
gradually larger upward, the upper I-1.5 mm. long and 0.25-0.5 
mm. wide, oblong-lingulate, broadly acute and somewhat apicu- 
late or rounded and blunt at apex, the margin more or less revo- 
lute nearly all round and entire or slightly crenulate in the upper 
part; costa stout, vanishing a little below the apex or percurrent, 
smooth on the back or papillose in the upper part, in cross-section 
showing two to four guide-cells with one or two layers of somewhat 
smaller cells on the ventral side and on the dorsal side mostly a 
distinct stereid band with outer cells slightly or not differentiated ; 
cells in upper part of leaf mostly obscure, densely papillose with 
partly C-shaped papillae, more or less four-sided, about 8 y in 
diameter, those of lower part pale, smooth, about 12 wide and 
from nearly square to two or three times longer than wide; peri- 
chaetial leaves about like those of stem, the inner sometimes 
smaller; seta erect, up to 1 cm. long, often strongly twisted below 
to the left and above to the right; capsule nearly straight and 
erect, 2 mm. long, with stomata in one row in the short, scarcely 
distinct neck; peristome variable, pale to reddish brown, finely 
Papillose throughout, the basilar membrane extending usually a 
little above the rim of the capsule and either bearing slightly ob- 
lique teeth once or twice divided into slender forks of unequal 
