296 



THALLOPHYTES. 



Antheridia andPistUUdia^much as in moss- 

 es, variously situated. Thecw stalked, open- 

 ing by irregular fissures or separate teetli. 

 Sjyores globose, usually mixed with spiral 

 elaters. This order lias been subdivided 

 into — 1. Marcliantie?e, thecee bursting ir- 

 regularly. 2. Jungermanniea?, thecee open- 

 ing by lour valves. 3. Eiccieae, thecoB bursting irregularly, 

 out elaters. 



witli- 



Genera. — Marcliantia, Jungermannia. 



Fig. 218, a, spore-case of Jungermannia hyalbia, ripe and bursti 

 very joung, covered Avitli its calyptra; c, elater and spore 



h, the same 



Class Y. — ^TuALLornYTES. 



567. LicHENES, Lichens. — Plants forming a thallus, which is 

 either foliaceous or crustaceous. They arc 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 cujds or shields resting on the surface of 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, Parmelia, Cetraria, Cenomyce, Baeomy'ces, XJsnea. 

 Fig. 219, «, a portion of the thallus of Variolaria amara ; 6, apiece of the thalhis 

 of Sticta pulmonacea ; c, thallus of the same, bearing shields. 



Fig. 219. 



Fig. 220. 



Fig. 220, d, Cetraria islamUca; ss, its shields; c, a shield magnified and divided 

 vertically. 



568. Fungi, Mushrooms^ Ifolds^ c&c. — ^These are parasitical, 

 or grow upon decayed organic substances, or soil aj-ising from 

 their decomposition. The plants belonging to this order con- 

 sist of cells, sometimes round, sometimes elongated, in the form 



