CRYPTOGAMIA. 221 



of vegetation. '* They are leafless, flowerless, perennial 

 plants, with a thallus, and external disk, containing spo- 

 rules." Lindley. The thallus is the frond, or crustaceous. 

 leaf-like expansion, which forms the principal surface of this 

 kind of vegetation. The sporules, or seeds, are usually con- 

 tained in the shields, or cup-like receptacles which are dis- 

 persed over the thallus, or leaf-like expansion. Sometimes 

 these little cups sit on the thallus without any pedicel, or foot- 

 stalk, and sometimes they are elevated above it, by stalk-like 

 processes, called podetia. In some spepies, the fruit is em- 

 bedded in the frond. This order of plants is chiefly found 

 on old fences, whether of wood or stone, on dry rocks, and 

 on the bark of trees exposed to the air and light. No Lichen 

 is found in the water ; and in wet places, Dr. Lindley says 

 their shields, or cups, are not produced. 



One thousand species of this order have been minutely 

 examined and described by authors, and probably as many 

 more exist which remain unnoticed. 



GENUS Calicium. Name from the Greek, kalukion, a little 

 cup, because the seed vessels are in the form of minute 

 cups. 



The upper figure represents one of the F '- 217 - 



species of this genus of its natural size, 

 the lower one is magnified, showing 

 more distinctly the form of the cups. 



This plant grows on decayed wood. 

 Crust or thallus thin, whitish and powde- 

 ry ; disk flesh-colored, becoming brown ; 

 stalks naked, becoming brown or black. 



There are several plants of this order which are employed 

 for economical purposes, and one, (the celebrated Iceland 

 Moss,) which is of great consequence in Arctic countries on 

 account of its being the chief food of the rein-deer. 



GENUS Lecanora. This genus contains two or three spe- 

 cies which afford purple dyes, and are employed in coloring. 

 Cudbear, (Lecanora tartarea,) one of these, has become an 

 article of commerce to a considerable extent as a coloring 

 drug. Cudbear is a corruption of Cuthbert, the person's name 

 who first brought it into use. It comes chiefly from Nor- 

 way ; but it is said that many an industrious man obtains his 



For what economical purposes are some c f the lichens employed ? 

 19* 



