506 



ILLUSTRATIONS OF THE NATURAL ORDERS. 



the upper they draw their nourishment directly from the air. The 

 fructification is in cups, or shields {apothecia), resting on the surface 

 of the thallus, or more or less immersed in its substance, or else in 

 pulverulent spots scattered over the surface. A magnified section 

 through an apothecium (Fig. 1324) brings to view a stratum of 

 elongated sacs (asci), with filaments intermixed, as seen detached 

 and highly magnified at Fig. 1325. Each ascus, or sac, contains a 

 few spores : these divide into two, which, however, generally remain 



1321 



132S 



1327 



mM9p ^. 



1322 



coherent. For a description of the Lichens of this country, the 

 student is referred to Professor Tuckerman's Synopsis of the Li- 

 chenes of New England, the other Northern States, ^-c. and to his 

 Lichenes Amer. Sept. Exsiccati, illustrating them by named speci- 

 mens. 



FIG. 1322. A stone upon which several Lichens are growing, such as (passing from left to 

 right) Parmelia conspersa, Sticta miniata, Lecidea geographica (so called from its patches re- 

 sembling the outline of islands, &c. on maps), &c , &c. 1323. Piece of the thallus of Parme- 

 lia conspersa, with a section through an apothecium. 1324. Section of a smaller apothecium, 

 more magnified. 1325. Two asci and their contained spores, with the accompanying filaments, 

 highly magnified. 1326. Section of a piece of the thallus of Sticta miniata, showing the im- 

 mersed apothecia. 1327. Cladonia cocciuea, bearing its fructification in rounded red masses 

 on the edges of a raised cup. 



