1869.] ^^^ [Wood. 



Thallus at first subglobose, afterwards frequently fusiform, blackish 

 green, slippery, firm ; filaments aeruginous, very elongate, sometimes 

 not articulated, but more generally shortly articulated, sometimes 

 strongly contracted at the joints ; apices sometimes truncate but gener- 

 ally produced into a long, flexuous, translucent hair ; sheath transpar- 

 ent, close, frequently truncate at the apex ; heterocysts globose or sub- 

 globose. 



Diam. jJ^tj"=MQ2G." 



Hab. In aquario meo. 



GEN. MASTIGOTHRIX. 



M. FIBROSA. Sj). Nov. 



M. trichomatibus dilute caeruleo-viridibus vel olivaceis vel sub- 

 aerugineis, infra hand articulatis, supra saepe breve articulatis ; 

 apice in trichomatibus maturis in setam hyalinam, distincte articu- 

 latam, longam, producto ; vaginis achrois, in filamentis immaturis, 

 distale distinctis, latis, hyalinis, infra modice crassis, arctis— in trichoma- 

 tibus maturis infra arctis, et indistinctis, supra in fibetillis dissolutis, in 

 apice, absentibus ; cellulis perdurantibus globosis interdum geminis. 



Filament either light bluish green or olivaceous or subaeruginous, belovi^ 

 not articulate, its upper portion often shortly articulate ; apex produced in 

 the mature filament into a hyaline seta, which is long and distinctly ar- 

 ticulate ; sheath transparent — in the immature filament, distally distinct, 

 broad, hyaline, but proximally close and rather thick — in the mature 

 filament below close and rather indistinct, and superiorly dissolved in fibril- 

 lae so as to be entirely wanting at the apex ; heterocysts globose, some- 

 times in pairs. 



Diam. trichom. 23V0" ; cell, perdur. t8ooo"-T8ooo"- 



Hab. In strato mucoso cum algis variis, in rupibus irroratis prope 

 Philadelphia. 



FAM. SCYTONEMEACEAE. 

 GEN. SCYTONEMA. 



S. CATARACTA. Sp. NoV. 



S. rupicola, caespitosum, fusco-atrum, longe et late expansum ; tri- 

 chomatibus flexuosis, flexilibus, fere 0.25" longibus, vage pseudoramo- 

 sissimis, superficie laeve ; pseudoramis elongatis, singulis, rarissime 

 geminis, liberis, interdum fuscis, saepius hyalinis, apice plerumque 

 truncato, rare nonnihil attenuato, saepe barbato, haud rubello ; tricho- 

 matibus internis aerugineis, tenuissimis, plerumque distincte articulatis ; 

 articulis diametro plerumque brevioribus, sed interdum longioribus, 

 saepe sejiuictis, saepe subglobosis ; vaginis crassis et firmis ; cellulis per- 

 durantibus et basilaribus et interjectis, singulis, rarissime geminis. 



Diam. trich. c. vag. plerumque .00045" ; max. .0011" ; sine vag. max. 

 .00013." 



S. Forming on rocks an extended turf-like stratum of a brownish 



