29 



The latter contains the plants ufually called Tremella, which M. Decandolle, 

 under Vaucher's generic name, has here reftored to their place in the vegetable 

 kingdom. 



Rivularia. — Alembrana fubcartilaginea, lobata aut rantcfe, muco gelati- 



nofo obteila. 



This however is not Dr. Roth's genus, but rather the fame with TJlva of 



Vaucher, and contains, ift. his U. gelatinofa, under the name of R. tubulofa. 



2d. Ulva lubrica of Roth. 3d. R. fcetida, which is probably my C. fcetula, 



and 4th, a new fpecies, with the name of R. Halleri. 



Ulva.— Frondes membranacea. Scmina fub epidermide latitantia, fapius 

 aggregate, frond is ipfius deflruBione exeuntia. 

 This genus in addition to mod of the Ulva, comprifes all the Ulva-lih Fuci, 

 with F. digitatus, F. bulbofus, F. foment of us, &c. 



Fucus. — Alga marina membranacea aut flamentofa. Capfula out femina 



aggregata in tuberculos nunc lateralis, nunc terminales, apice poro dchf- 



centts. 



The genus as here conftituted comprifes a part only of the plants ufually 



called by the name of Fucus, fome having, as is above ment'oned, been removed 



to the Ulva, and F. pinajlroides and F. flum to the following family. Ulva 



plumofi, which Dr. Roth has carried to his genus Confrva, is here, and with 



equal impropriety, defcribed under the name of Fucus arbufcula. 



Ceramium. — Stii pes flamentofa marina ftmplicet aut ramofa, dijfepimentis 



tranfverfalibus nodofo-articulata ; tubercula polyfperma fub globofa latiralia 



aut terminalia. 



The fpecies of Dr. Roth's fecond divifion of Ceramium, 'flis fpurie genicu- 



fotis' conftitute this genus, and thofe of the firft divifion are fent back to the 



Fuci. 



DlATOMA. — Planta pfeudo-parafttica oculo nudo vix confpicua, filamentis 

 ftmplicibus articulatis, articulis in adulta planta tranfverfim feilis. 

 The fpecies arranged in the fecYion " articulis folutis" of my fynopfis, confti- 



