x62 Minnesota Algae 



2 Plant mass small, adherent, somewhat globose; orange or green; 



trichomes 2-2.5 mic. in diameter, very^ short, strongly curved 



N. aureum 



3 Plant mass small, gelatinous, membranaceous, soft, green, blue-green 



or brownish; trichomes 3-4 mic. in diameter, flexuously curved, 

 somewhat densely entangled N. comminutum 



IV Plants living in fresh water; plant mass large, gelatinous, fragile, 



at first spherical, afterwards becoming torn and irregularly ex- 

 panded. 



1 Filaments numerous, abruptly contorted, entangled; trichomes 3.5-4 



mic. in diameter; gonidia 6-7 mic. in diameter, 7-8 mic. in length 



N. linckia 



2 Filaments flexuous, loosely entangled 



(i) Gonidia 6-7 mic. in diameter, spherical; wall of gonidium smooth; 



trichomes 4 mic. in diameter N. piscinale 



(2) Gonidia oblong; wall of gonidium smooth 

 A Trichomes 4-4.2 mic. in diameter; gonidia 6-8 mic. in diameter, 

 7-10 mic. in length, contiguous; wall of gonidium becoming 

 brownish or colorless N. rivulare 



B Trichomes 3.5-4 mic. in diameter; gonidia 6 mic. in diameter, 8-10 

 mic. in length, not contiguous; wall of gonidium colorless 



N. carneum 

 C Trichomes 4 mic. in diameter; cells different in shape, some 

 cylindrical, others barrel-shaped or spherical depressed; gonidia 

 6-7 mic. in diameter, 10-12 mic. in length, not contiguous; wall 

 of gonidium colorless or becoming yellowish 



N. spongiaeforme 



V Plants living on soil; colonies gelatinous, soft, at first spherical, soon 



confluent and flattened, attached to soil or mosses 



1 Cells cylindrical; trichomes 4 mic. in diameter; gonidia 6-8 mic. in 



diameter 



(i) Gonidia 14-19 mic. in length; wall of gonidium smooth 



N. ellipsosporum 

 (2) Gonidia 8-14 mic. in length; wall of gonidium furnished with 

 short spines N. gelatinosum 



2 Cells oval, spherical or spherical depressed 



(i) Trichomes 3-4 mic. in diameter; gonidia 4-8 mic. in diameter, 

 8-12 mic. in length, oblong, in a catenate series 



N. muscorum 



(2) Trichomes 2.2-3 mic in diameter; gonidia 4 mic. in diameter, 6 

 mic. in length, oval N. humifusum 



VI Plants living on soil, sometimes submerged; colonies free, at first 



spherical, then expanding symmetrically or irregularly; cells 

 somewhat globose. 



I Colonies gelatinous, spongy, lacunose, somewhat pellucid, green, olive 

 or brownish; trichomes 4 mic. in diameter; gonidia 7 mic. in diame- 



