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CHAPTER XII. 
DECEMBER. 
A BRIEF mention of Lichens, Funguses, and Sea-weeds, 
will form the last part of this branch of Natural History. 
The reader must refer to works devoted to this portion of 
the subject, when more information is required. 
Licnmnns. Jichens. The characters of the order are as 
follows. Aerial plants (not deriving nourishment from the 
soil). Leaves and stem combined, and spreading either hori- 
zontally in the form of a lobed irregular plate, or rising erect 
with irregular branches, having disks or shields which pro- 
duce the seeds. 
Lichens are very valuable in preparing the ground for 
more important vegetables; they retain much moisture, and 
