.50 G 



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 



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

 student is referred to Professor Tuckerman's Synopsis of the Lu 

 chenes of New England, the other Northern States, S>-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) ParmeHa conspersa, Sticta miniata, Lecidea geographica (so called fro.n 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 thiough an apothecium. 1324. Section of a smaller apothecium, 

 more magnified 1325. Two asri and their contained spores, with the accompany ing filaments, 

 highly magnified 1320. Section of a piece of the thallus of Sticta miniata, showing the im. 

 mersed apothecia. 1327. CladonU coecinea, bearing itJ fructification iu rounded red masses 

 ou the edges of a rai.-ed cup. 



