14St NEW ARRANGEMENT OF 
Veget. The steins are sometimes branched, but in the 
greatest number of the species extremely short. In P. ser- 
ratum and coharens they are apparently absent, but really 
present under the form of surculi, or creeping articulated 
conferva-like shoots, destitute of foliage, upon which the 
fructification with its perichaetial leaves is sessile; 
The cauline leaves of all the species are furnished with 
a nerve, and are in general reticulated. In this character, 
the perichaetial leaves of P. serratum^ colKerens, and some 
others, are remarkable, the cellules being large, and evident 
under a small power of the microscope. They vary in 
shape, from ovate, in P. curvicollum and patens, ovato- 
apiculate, in P. rectum, to lanceolate and subulate in other 
species. Their situation is generally along the stem, with- 
out any particular order ; but in P. alternvfolmm they are 
beautifully alternate. Serratures are found in some few 
species, but those with subulate leaves are always entire. 
The perichaetial leaves are for the most part uniform with 
the cauline ones ; but in P. altermfolium they are much 
larger and longer, and surround the theca. 
Obs. Two of the species of this genus are apparently at 
variance with the generic character, P. alternifolium and 
axillare ; in both, the seta appears to be truly lateral. In 
consequence of this, Bridel has made a new genus of the 
former, under the name of Pleuridium^^' Capsula latera- 
lis inaperta decidens, calyptra decidua and adds another 
species, Pleuridium globiferum, from the Isle of France, 
which seems to be merely a variety. In P. alternifolium, 
the theca is, however, really terminal, or, at the summit of 
small branches, situated on the main stem. It is the short- 
ness of this branchlet which deceived Bridel : but an ac- 
curate inspection shows, that it is also clothed with cauline 
leaves, and not with the long perichaetial ones alone ; the 
