Conferva. — Tubuli vel- filaments herbacca imernis parietilus fruSiijicatio- 

 num granulis adfperfa. 



This genus, ftill more than Ceramium, comprifes plants belonging to feveral 

 natural families, perfectly diftincr. from each other, and the learned Doclor 

 feems to have ufed it as a receptacle for all thofe fpecies of which the fruc- 

 tification is unknown, or which he could not otherwife difpdfe of. They are 

 arranged under two feparate heads, " Tubtilof*," and " Filamentofe." Of thefe, 

 the former is compofed of the tubular Ulva, the union of which with the 

 Conferva appears to me to be by no means warranted by what is at prefent 

 known on the fubject. The latter has three main divifions, depending on what 

 are here termed genlcula, but which are in the courfe of this work (perhaps im- 

 properly) named Dijppiments. I have ufed this word to exprefs every fort of 

 divifion between the veficles or articuli of thefe plants. It ;would certainly be 

 defirable to diltinguiih, by different names, the different natures of thefe 

 divifions, but they are often fo ambiguous, and in plants fo minute it is necef- 

 farily fo difficult to examine them accurately, that I have not ventured to under- 

 take the talk. 



The only Britifh fpecies' arranged in the firft ■ divifion, " Conformes fen con* 

 t!rut,t," are C. fenejlralis, Ulva plumcfa, and C. dilatata, refpecYing which I 

 muft be allowed to remark, that this arrangement of C. fenejlralis is erroneous, 

 as diflepiments may be obferved in the filaments when examined with the 

 higher powers of a microfcope, while U. pltimofa is at leaft a plant of doubtful 

 place in the fyftem, and C. dilatata is the fame with my C. veftcata, and fliould 

 therefore in this arrangement have been placed with C. amphibia, among the 

 Ccramia. 



The fecond divifion is entitled " Articulate, geniculis fpuriis." Dr. Roth 

 calls thofe diflepiments fptirious, which have their origin in the internal ftruc- 

 ture, and not in the fibres which conftitute the filament. This fection is itfelf 

 thrice fubdivided. 



The firft fubdivifion is termed " Sporangiorum arinulis". In thefe plants, Dr. 



B 



