117 
faction. The teeth, as soon as they are removed from the grooves 
of the endostome, in their upper two-thirds, curve outwardly so 
that their margins approximate, thus becoming obtusely trique- 
trous, the segments behaving in like manner. 
Dirricuum AmBIcuuM, n. sp. Dioicous; loosely caspitose; stem 
rather stout, about I cm. long, arcuate-erect, with one or more 
innovations. Leaves pale yellow, shining, crispate when dry, 
accrescent upwards, lanceolate-subulate, patent-subsecund, 
flexuose ; lower erect at the half-clasping short base, lanceolate; 
upper with oblong-erect bases, long lanceolate-subulate, con- 
cave, the slightly thickened-involute margins sinuate-dentate; 
the perichetial with longer sheathing bases, not abruptly nar- 
rowed: costa percurrent and dentate on the back in the upper 
third. Areolation linear, oblong, indistinct above; walls thick, 
tortuous, striate Seta reddish below, paler above, long, flexu- 
ose. Capsule cylindrical, 0.3 cm. long, narrow, straight or 
slightly curved, reddish, dark brown when deoperculate. 
Operculum conical-rostrate, blunt, nearly or quite erect, about 
one-third the length of the capsule. Exothecial cells quad- 
rate-oblong, thick-walled, irregular with a row of smaller ovate- 
quadrate cells at the mouth. Teeth reddish, long, straight, 
papillose, nearly or quite split to the rather broad-basal mem- 
brane; legs filiform except at the slightly flattened connate 
bases, equal and regular. Annulus large, adherent. 
Habitat: moist banks. Mason Co., Washington, Mr. C. V. 
Piper. 
Remarks: Somewhat larger and with firmer cells, yet the 
leaves of D. ambiguum bear a certain resemblance to those of the’ 
variable D. ‘ortile (Schrad.) Hampe, the capsule and lid to J. 
tenutfolium (Schrad.) Lindb. ( Zrichodon cylindricus, Schimp.), while 
the peristome differs from that of either. In D. éortile the leaves 
are reflexed to the middle, the capsule oblong-cylindrical, the 
operculum conical, short-beaked, and the peristome of a more rudi- 
mentary type. In D. senuifolium the exothecial cells are linear- 
rhomboidal, the teeth flattened to above the middle, roughened 
but not papillose,* the squarrose leaves abruptly narrowed, and 
the basal membrane not as wide. Notwithstanding .the tortuloid 
peristome this moss is evidently a Ditrichum, most closely allied 
to D. tenuifolium, yet quite distinct. 
Rosemont, N. J. 
* Braithwaite’s British Moss Flora, i. 97. 
