44 
NEW ARRAKGEMENT OF 
Feuct. Calyptra dimidiate, large, either closely em- 
bracing the theca, or inflated, and then sometimes quadran- 
gular and pyramidal, persistent, and, in consequence of a 
lateral fissure, which then takes place midway between the 
base and the apex, becoming eventually pseudo-mitriform. 
Seta terminal, but sometimes apparently lateral from inno- 
vations ; generally much longer than the perichsetiai leaves ; 
similar in colour to the theca ; rigid, straight, or flexuose ; 
in one species, of a whitish colour, thick, and carnose. 
Apophysis rarely any ? Theca entire, subgloboscj hemi- 
spherical, turbinate, ovate, oblong or cylindrical, or even 
angular, equal, or sometimes so contracted in the middle as 
to appear furnished with an apophysis ; varying in different 
species, but tolerably constant in the same ; the orifice is 
sometimes contracted, but more frequently large, naked ; in 
some instances furnished with an annulus, reddish-brown, 
smooth, striated or sulcated. Operculum deciduous, of the 
same colour as the theca, oblique, rostrate, conical or mam- 
millose, acute or obtuse, always entire. Peristomium none. 
Columella, when mature, usually shorter than the theca, in 
some species, however, exserted, and even adnate with the 
operculum ; mostly filiform or clavate, straight, rarely large, 
obconical, or rather infundibuliform. Sporulce various. 
DiFF. Char. Calyptra dimidiate. Seta terminal Mouth 
of the theca naJced. 
Veg. The stems of the Gymnostoma are extremely va- 
riable in length. In some species there is scarcely any at 
all ; in others they are longer, but still simple ; while in 
several they are much elongated, and repeatedly branched. 
The former^ as might be expected, grow either in a solitary 
or tufted manner; the latter closely matted and inter- 
woven together. The leaves present a reticulation curiously 
