506 



ILLTJSTKATIONS OF THE NATURAL ORDERS. 



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

 fructification is in cups, or shields (apotkecid), '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 asms, 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 Li- 

 chenes of New England, the other Northern States, SfC. 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 ininiata, 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 coccinea, bearing its fructification in rounded red masses 

 on the edges of a raised cup. 



