THE MOSSES. 99 
extinct unknown Mosses, which were very nearly related 
to the lowest liverworts of the present day. In the 
history of creation, Ferns are of greater importance than 
Mosses. 
The branch of Mosses (Muscine, also called Musci, or 
Bryophyta) contains the lower and more imperfect plants of 
_ the group of Prothallophytes, which as yet do not possess 
vessels. Their bodies are mostly so tender and perishable 
that they are very ill-suited for being preserved in a recog- 
nizable state as fossils. Hence the fossil remains of all 
classes of Mosses are rare and insignificant. It is probable 
that Mosses developed in very early times out of the Thallus 
plants, or, to be more precise, out of the Green Algz. It is 
probable that in the primordial period there existed aquatic 
forms of transition from the latter to Mosses, and in the 
primary period to those living on land. The Mosses of the 
present day—out of the gradually differentiating develop- 
ment of which comparative anatomy may draw some infer- 
ences as to their genealogy—are divided into two different 
classes, namely: (1) Liverworts; (2) Leafy Mosses. 
The first and oldest class of Mosses, which is directly 
allied to the Green Aleve, or Confervee, is formed by the Lwer- 
worts (Hepatic, or Thallobrya). The mosses belonging to 
them are, for the most part, small and insignificant in form, 
and are little known. Their lowcst forms still possess, 
in both generations, a simple thallus like the Thallus plants ; 
as for example, the Riccize and Marchantiaceze. But the 
more highly developed liverworts, the Jungermanniaceze 
and those akin to them, gradually commence to differentiate 
stem and leaf, and their most highly-developed forms are 
closely allied to leaf-mosses. By this transitional series 
