2IO 
STRUCTURE AND LIFE HISTORIES 
in little pits or depressions on the upper surface. The 
habitat of the liverworts illustrates a step forward in the 
abandonment by plants of a wholly aquatic life and the 
establishment of a land vegetation; but the prevailingly 
moist situations in which most of the species are found, 
FIG. 153. Anthoceros fimbriatus. Portion of a thallus viewed from 
below, with the rhizoids omitted. The one-layered crisped lobes at the 
margin serve to retain moisture. (After Goebel.) 
and the need of water for fertilization by swimming 
sperms (soon to be described), points to an ancestral 
habitat truly aquatic. 
193. Description of the Plant Body. The plant body 
of the liverworts shows a marked departure from that of 
the mosses in the direction of simplicity. There are four 
main groups or orders of Hepaticae, as follows: 
Hepaticae 
1. Ricciales. 
2. Marchantiales. 
3. Jungermanniales 
4. Anthocerotales. 
