70 CRYPTOGAMIA LICHENES. 



This phenomenon is peculiar to the family, and appears to be 

 owing, according to the observations of RAMOND, to the extrava- 

 sation of a peculiar juice contained in the little cells. The fruc- 

 tification consists of tubercles, or raised letter-like lines bursting 

 through a crust, or of round saucer-shaped or shield-like disks, 

 with or without an adventitious border, and in the substance of 

 which disks the seeds are probably lodged. The fructification, 

 whatever may be its form, is termed Apothecia. 



LINNAEUS included the Lichens in a single genus ; and the 

 first attempt to introduce, to English botanists, a better arrange, 

 ment, was made by the authors of the Botanist's Guide through 

 the counties of Northumberland and Durham, published in 1807- 

 They, however, gave definitions neither of the genera nor species 

 of the Acharian method which they adopted, a deficiency which, so 

 far as the former were concerned, was well supplied in the article 

 Lichen, written for Dr BREWSTER'S Edinburgh Encyclopaedia by 

 PATRICK NEILL, Esq. an article of much interest, and of which 

 I have freely availed myself. Since that time the arrangement 

 of ACHARIUS has been followed by all British naturalists, with 

 perhaps some injustice to authors of not less reputation than the 

 Swede, who too little regarded the labours of some of his prede- 

 cessors. WAHLENBERG complains of this openly (Fl. Lap. p. 400.), 

 and HOFFMAN and DE CANDOLLE had not less reason of com- 

 plaint. The French and Germans still, I believe, decline to 

 adopt the method of ACHARIUS, but, in a local Flora of this kind, 

 it would be injudicious to depart from established custom, al- 

 though the names of others have the claim of priority, and al- 

 though 1 feel persuaded that the genera might with propriety be 

 reduced in their numbers. 



Apothecia saucer-shaped or peltate, with a raised border, (In age 

 the disk sometimes becomes convex, so that the apothecice resemble a 

 tubercle, but the border is permanent, and always distinguishable. ) 



\ Frond foliaceous or crustaceous, oppressed or adnate. 



9. PEL TIDE A. Frond foliaceous, spreading, lobed, with woolly 

 veins beneath. Apothecia roundish, terminating the lobes, 

 superior, the border thin, and formed from the frond. 



