711 
Caespitosa, nalans, radiatim expansa ; fila 10-15 /x crassa; vaginae 
parce lamellosae *S'. tolypothrichoides 
Natans, filis 12-18]^ crassis ; vaginae crassae lamellosae; tricho- 
m;Ua passim incrassata (9 15 S. ftavo-viride 
Terreslris, pannosa, expansa; fila 15-21 p crassa; vaginae hic illic 
lamellosae, in vertice ultimae cellulae tenues S. figuratum 
Terrestris, pannosa, expansa; fila 18-3G crassa; vaginae usque 
ad verticem ultimae cellulae crassae, pluries ochreatae S. Myochrom 
Sectio III. Vaginae crassae, lamellosae, e stratis plurimis ochreatis 
formatae; ramificatio duplex: rami inferiores gemini (scytonematoidei), 
superiores solitarii (tolypotrichoidei), heterocysta basali praediti (Peta- 
lonema). 
Caespitoso-crustacea, nigra ; fila 0,5-2 mm. alta, 15-30 (x crassa 
rami gemini interne coaliti, demum liberi S. cruslaceurn 
Gaespitoso-pulvinat), nigra ; fila in fascicules coalita, 3-5 mm. alta, 
12-30 crassa ; cellulae (in sicco) subsphaericae S. velutinum 
Planta in stratum spongiosum, compactum, viridi-fuscum expansa ; 
fila coalita, 2-3 mm. alta, 15-30 p crassa, vaginarum strata interiora 
flava, exteriora hyalina, mollia, ambitu irregulari S. involvens 
Pulvinata, nigra; fila libera, millim. a'ta, 27-45 /x crassa; vaginae 
multipliciter ^meilosae, erosae S. crassum 
Pulvinata, nigra; fila libera, millim, alta, 24-40// crassa; vaginae 
dense lamellosae, lamellis arctis S. densum 
Fila sparsa vel in stratum mucosum approximala, libera, 5-8 mm. 
alta, 24-06 // crassa; vaginae teretes, multipliciter lameliosae, discolores, 
saepe constrictae S. alatuni 
Tolypothrix Kuetz. 
A* Vaginae tenues. 
t Gaespitosae, saepius natantes, pseudo-ramis patentibus ; vaginae 
ad basin ramorum saepe inflatae ; heterocystae saepe ad basin pluri- 
mae. Plantae in acpiis tranquillis crescentes. 
Fila 10-15// crassa; articuli brèves, juniores doliiformes 
T. distorta 
Fila 9-12,5 IX crassa ; articuli diametro aequales vel longiores 
T. lanata 
Fila 8-10 p. crassa, articuli diametro aequales vel longiores 
T. tennis 
