they are inferior in the vegetative system. There is no prototype 

 of fructification among the Algae, which has not in the Fungi its 

 ectype more perfectly developed. (Cf. Fries. Syst Mycol. i. xxn., 

 Lichenogr. p. xn.) The Algae, moreover, having gonidia, or repro- 

 ductive buds, are hence successively explicated ; absorb and pre- 

 pare nutrition from the surrounding element ; and depend less upon 

 place ; propagating, moreover, more frequently, and in the lowest 

 forms only, by gonidia : the Fungi, on the contrary, wanting go- 

 nidia, have no successive evolution, and propagate normally by 

 sporidia. (Compare the two classes of Homonemeae in the Clavis 

 to Fries's system, given in the previous essay.) 



ALGJE are either aerial, (amphibial,) or aquatic, and fall into three 

 Orders, Lichenes, Byssacese, and Phyceae, which are distinguished 

 as follows : 



Aerial Algce, or Lichenes, are perennial, with interrupted vegeta- 

 tion (that is, subject to apparent death and revival, according as 

 they are conditionated by moisture or drought); exogeneous, and 

 forming distinct layers. Amphibial Alga, or Byssacece, are peren- 

 nial, with vegetation at intervals retarded ; heterogeneous, and not 

 forming distinct layers. Aquatic Alga, or Phycea, have an uninter- 

 rupted vegetation, and are either endogeneous and multiplied by 

 sporidia and gonidia FucacecB : or homogeneous and without 

 apothecia or true sporidia, and hence multiplied only by gonidia 

 Ulvacea. 1 



Obs. The order Byssacese, as separated and defined by Fries, 

 seems necessary in the system, at least ; and the plants composing 

 it are well distinguished from Lichenes and Phycese, both by char* 

 acters and habit. (Cf. Fl. Scanica, p. 291, Linnaea, 1830, p. 535, 

 Lichenogr. reform. Prael. n., which may be compared with the 

 author's earlier views in Stirp. Femsjo, p. 41.) 



Character Phytographicus LICHENUM : Apothecia nucleo ascigero, 

 raro primitus pulveraceo-collapso. Thallus strato infra corticale 

 discrete. 



BYSSACEARUM: Apothecia ascigera, raro in ascos dissoluta. 

 Thalli strata, corticale et medullare, confusa. 



FUCACEARUM : Apothecia e thallo formata, sporidiis peridiolis aut 

 muco involutis. Thalli stratum exterius, haud discretum, corticans, 

 gonidiis sparsis. 



ULVACEARUM: A potheciaet sporidia nulla. Thallus absque stra- 

 tisdissimillibus et discretis, gonidiis sparsis, sporidiorum vicibus fun- 

 gentibus. 



Character Typicus LICHENUM : Stirpes radice (cellulis Jistulosis), 

 trunco (lepra) et foliis (gonidiis} in unum corpus corticatum confu- 

 sis, sed in stratis discretis, fructificatione metamorphosi simplici enata. 



BYSSACEARUM: Stirpes radice trunco et foliis cum strato corticali 

 confusis, nullis stratis discretis; fructificatione simplici metamor- 

 phosi enata. 



FUCACEARUM : Stirpes radice et foliis in corpus truncosum aut 



1 Fucaceae and Ulvacece are used by Fries sensu /atiori, to indicate the two 

 great sections of Aquatic Alpse- They correspond, respectively to the Asco- 

 phycae, and Gongylophycse of Reichenbach. 



