SECTION II. 



SYSTEM OF ROTH. 



Dr. Roth has divided the fubmerfed Algse into the following Genera : 

 Fucus, Ceramlum, Batrachofpennum, Conferva, Mertenfia, Hydrodiilyon, Viva, 

 Rivularla, Linkla, and Tremella. I {hall give the outline of each of thefe, and 

 offer a few remarks on thofe that contain ajiy of the plants ufually denominated 

 Confervx. 



Fucus. — V-eficuU aggregate fubftantia frondis immerfa, ports mucifiuis 



pradila. 



This genus, of which the definition is as vague and unmeaning as the fame 



number of words can well be, is intended to comprehend a part only of the 



plants ufually called by the name of Fuel, the remainder having been referred 



ro the following. 



Ceramium. — Fllo numlranaceo-cartllaglneat capfulis granuliferh ipfis 

 adnatis. 

 In this genus are made two divifions ; the firft, 'fills eotiformibus,' contains 

 fome of the more (lender Fuci, and of the unjointed capfuliferous Confervx : 

 the other, 'fills fpmle genieulatis,' comprehends the jointed Fuci, and the re- 

 mainder of the capfuliferous Confervx. There is undoubtedly a great fimilarity 

 in the fructification of the capfuliferous fpecies, and yet feveral natural tribes, 

 if not really diftintf families, may be perceived among them, although, as has 

 been already obferved, the imperfect ftate of our knowledge, would render 

 it imprudent to attempt at prefent to define their refpective limits. I fhall 

 however enumerate thofe which appear moft ftriking. 



The unjointed fpecies probably all belong to the genus Vaueherla, as will be 

 hereafter mentioned. 



C. ekngata, as is obferved in die defcription of that fpecies, has two kinds of 



