43 
Classification of the Bryophyta. 
Pleuroziaceae. 
Porellaceae. 
Lej euneaceas. 
IV. Anthocerotales. 
Anthocerotaceas.— Anthoceros, Notothylas, Megaceros, Den- 
droceros. 
V. Sphagnales. 
Sphagnaceae.— Sphagnum. 
VI. Andreaeales: 
Andreasaceas.— A ndrecea. 
VI. Tetraphidales. 
Tetraphidaceae.— Tetraphis , Tetradontium , Calomnium. 
VIII. Polytrichales. 
Dawsoniaceas.— Dawsonia. 
Polytrichaceas.— Polytrichum, Catharinea, Lyellia, etc. 
IX. Buxbaumiales. 
Buxbaumiaceae.— Buxhaumia. 
Diphysciaceae.— Diphyscium. 
X. Eu-Bryales. 
The old-established primary division of the Bryophyta into the 
two classes Hepaticae (including the first four of the Orders 
enumerated above) and Musci has only been called in question in 
connexion with the two groups Anthocerotales and Sphagnales. It is 
of interest to note that in certain of the characters which have been 
used to exclude the Anthocerotales from the Hepaticae on one hand, 
and the Sphagnales from the Musci on the other, these two aberrant 
groups show a striking resemblance to each other. If the Antho¬ 
cerotales are to be made a separate class apart from the Hepaticae, 
either Sphagnales should also be considered a separate class apart 
from the Musci, thus making four primary divisions of Bryophyta— 
Hepaticas proper, Anthocerotes, Sphagna, and Musci proper—or 
the Anthocerotales and Sphagnales might be united to form a class 
intermediate between the “ Eu-Hepaticae ” and the “ Eu-Musci,” 
thus giving three classes of Bryophyta. The most striking character 
which is common to Anthocerotales and Sphagnales, as compared 
with the remaining Bryophyta, is the origin of the archesporium as 
a dome-like layer formed chiefly from the amphithecium and 
completed above across the endothecium, the columella—covered by 
