THE GENERA OF MOSSES. 
141 
Fruct. The calyptra is dimidiate, and very fugacious ; 
in some species, only a little shorter than the theca; in 
most, however, much shorter, and small in size : it is ten- 
der, of a whitish colour, and reticulated. The seta is ter- 
minal ; sometimes apparently lateral, in consequence of in- 
novations ; generally short, of a greenish- white colour and 
delicate texture; sometimes reaching the length of from 
two to six lines, when it is browner, and more rigid. An 
apophysis to the theca is a rare occurrence, but such a 
structure has been described by Dr Hornschuch to exist 
in one species, P. splachnoides. The theca is deciduous 
from the summit of the seta, entire, somewhat globose, or 
ovate, and not striated; generally reticulated, but some- 
times most beautifully and regularly chequered with trans- 
verse bands : the colour is more or less of a deep-brown ; 
in one or two instances, as in P. crassinervium and cuspu 
datum, it is, in a young state, completely surrounded by a 
remarkable coating of a thick subcarnose, pale-green and 
pellucid substance, which, when dry, bears a strong re- 
semblance to a large scariose calyptra previous to lacera- 
tion. The operculum is oblique, of a more tender struc- 
ture than the theca, never deciduous, but so united to the 
theca, and having the line of separation so inconspicuous, 
that one would almost be disposed to call it, less an oper- 
culum, than a short oblique termination of the theca. 
There is no peristome. The columella is here very vari- 
able ; long, and easily observed in P. rectum and curvicoh 
lum; but in most others, short, or apparently absent. The 
sporules are large for the size of the theca, angled, and 
tuberculated, varying much in regard to number, being 16 
in P. alternifolium, and about 100 in P. serratum. 
DiFP. Char. The theca deciduous from the seta ; the 
calyptra short, jfugacious. 
