TH^LOPHTTES. 
AntTieridia mdPistilUdia^miich as in moss- ^'s- 2^^- 
es, variously situated. Theece stalked, open- 
ing by irregular fissures or separate teeth. 
Spores globose, usually mixed with spiral 
elaters. This order has been subdivided 
into — 1. Marchantiese, thecse bursting ir- 
i*egularly. 2. Jungermannieae, thecse open- 
ing by four valves. 3. Kicciea?, thecae bursting i.i 6'^^ alarly, with- 
out elaters. 
Genera. — Marchantia, Jungermannia. 
Fig. 218, a, spore-case of Jungermannia hyalina, ripe a.ad /listing; 6, the same 
very young, covered with its calyptra ; c, elater and sp»ii't; 
Class Y . — ^Thallophi tes. 
567. LicHENES, LioTiens. — ^Plants forming a lliallus, »yhich is 
either foliaceous or crustaceous. They are found in all quarters 
of the globe, growing on the surface of rocks, the bark of trees, 
or sometimes upon the ground ; by their upper surface they 
draw most of their nourishment from the atmosphere. The 
fructification is in cups or shields resting on the surface ol the 
thallus and more or less immersed in its substance, or in pul- 
verulent spots scattered over the surface. 
a. Properties: used for food and for dyeing. 
Genera. — Gyrophora, Parmolia, Cetraria, Cenomyce, Bseomyces, XJsnea. 
Fig. 219, a, a portion of the thallus of Variolaria amara ; 6, a piece of the thallu? 
of Stiota pulmonacea ; c, thallus of the same, bearing shields. 
Fig. 219. Fig. 220. 
Fig. 220, d, Cetraria islandica ; s s, its shields ; e, a shield magnified and divided 
vertically. 
568. Fungi, Mushrooms, Molds, c&g. — These are parasitical, 
or grow upon decayed organic substances, or soil arising from 
their decomposition. The plants belonging to this order con- 
sist of cells, sometimes round, sometimes elongated, in the form 
