Wood.] 1'^" [Juii,el8, 



GEN. RIVULARIA. 



E. CAKTILAGINEA. Sp. NoV. 



R. subglobosa, parva, cartilaginea, saturate brunnea vel sub-a-tra, soli- 

 taria in plantis aquaticis : — tricliomatibus mattiris sterilibus rectis aut sub- 

 rectis, cylindricis, elongatis, baud articulatis ; cytioplasmate saepe inter- 

 rupto ; vaginis arctis et distinctis ; cellulis perdurantibus globosis, dia- 

 metro subaeqiialibus : — trichomatibus fertilibus rectis aut sub-rectis, supra 

 spora cellulis 8-9 instructis ; sporis elongatis, rectis, cylindricis ; vaginis 

 nonniliil crassis, arctis :— tricliomatibus immaturis, breve articulatis ; 

 vaginis subamplis. 



Frond subglobose, small, cartilaginous, deep brown or blackish, soli- 

 tary upon aquatic plants : mature sterile filaments, cylindrical, elongated, 

 not articulated, tbeir cytioplasm frequently interrupted, tlieir sbeatlis 

 close and distinct, their heterocysts globose and about equal to them in 

 diameter ; fertile filaments straight or nearly so, above the spores fur- 

 nished with 8 or 9 cells; spores elongate, straight, cylindrical; sheaths 

 rather thick, close ; immature filaments shortly articulate, their sheaths 

 rather large. 



Diam. trich. cum vag. aoVo" ? spor. goVo'''- 



Hab. In palude, Northern Michigan. 



GEN. DASYACTIS. 



D. MOLLIS. Sp. Nov. 



D. parva, ad magnitudinem pisi minimi, enormiter subglobosa, mol- 

 lis, gelatinosa, dilute viridis, baud distincte zonata ; trichomatibus pler- 

 umque subrectis, partim distincte, partim indistincte articulatis ; vaginis. 

 in trichomatibus maturis baud visibilibus, in trichomatibus juvenibus 

 supra subamplis ; cellulis perdurantibus sub-globosis, globosis, vel ellip- 

 ticis, diametro duplo majoribus, plerumque singulis sed interdum bi vel 

 triseriatis. 



Frond small, about the size of a small pea, irregularly subglobose, 

 soft, gelatinous, light green, not distinctly zoned; filaments generally 

 straightish, partly distinctly, partly indistinctly articulate; sheaths in 

 the mature filament not perceptible ; in the young filaments rather large 

 in the upper jjortion ; heterocysts subglobose or globose or elliptic, twice 

 as large as the filament, generally single but sometimes bi or tri-seriate. 



Diam trich J " 1 " ■ cell uerd J " 



XJLAlll. tllOll. I3Q00 4500 5 '^C-l^' pel LI. j^ g g g * 



Hab. In palude plantas aquaticas adhaerens, Northern Michigan. 

 GEN. MASTIGONEMA. 



M. ELONGATUir. 8p. JSfoV. 



M. initio subglobosum, postea saepe nonnihil fusinum, nigro-viride, lu- 

 bricum, firme ; trichomatibus aerugineis, valde elongatis, flagelliformibus, 

 interdum inarticulatis sed saepius breve articulatis, interduin ad genicula 

 valde constrictis ; apice interdum truncato sed plerumque in pilo, longo,* 

 achroo, flexuoso, producto ; vaginis achrois, arctis, saepe ai^ice truncatis ; 

 cellulis perdurantibus globosis vel subglobosis. 



