378 CRYPTOGAMIA. 



are Ulva, t. 419, 420, 1276, well defined by its 

 seeds being dispersed under the cuticle throughout 

 the membranous or gelatinous substance of the 

 frond ; Fucus, t. 1066 1069, &c., whose seeds are 

 collected together in tubercles or swellings, of va- 

 rious forms and sizes ; and Conferva, of which the 

 twenty-fourth and twenty-fifth volumes of Engl. 

 Hot., more especially, show various specimens. This 

 last genus is commonly known by its capillary, and, 

 for the most part, jointed frond. The seeds of some 

 species are lodged in external capsules or tubercles ; 

 of others in the joints of the frond ; and hence the 

 ingenious Dr. Roth has formed a genus of the for- 

 mer, called Ceramium. His Rwularia, Engl. Bot. 

 t. 1797 1799, is perhaps more satisfactorily sepa- 

 rated from Conferva, as we trust is Vaucheria, 

 1. 1 765, 1 766, a fresh-water genus named after M. 

 Vaucher of Geneva, who has published an elaborate 

 and faithful microscopical work on Fresh-water Con- 

 fervas. The submersed Alg<% in general are merely 

 fixed by the roots, their nourishment being imbibed 

 by their surface. Many of them float withouc being 

 attached to any thing. The genus Fucus has re- 

 ceived more botanical attention than the rest of this 

 tribe ; and the works of Gmelin, Esper, Stackhouse 

 and Velley have ascertained many species, which 

 the labours of Dr. Goodenough, Mr. Woodward 

 and Mr. Turner have reduced to systematic order. 

 Still a more perfect .combination of the skill of the 



