298 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



6. Lower cells 2-5 diam. long. i. S. lubricum var. varians. 



6. Lower cells 3-8 diam. long. 7. 



7. Ratuuli pointed. 2. S. amoenuw. 



7. Ramuli setiferous. 3. S. flagelliferum. 



8. Filaments short, tufted. 9. 



8. Filaments more elongate. 12. 



9. Of thermal waters. 7. S. thermale. 



9. Of ordinary temperatures. 10. 



10. Tips obtuse or short-pointed. 8. 5. nanum. 



10. Tips attenuate or setiferous. n. 



n. Ramuli scattered. 13. 



ii. Ramuli densely fasciculate. 10. S. glomeratum. 



12. Filaments 5-7 M diam. n. S. attenuatum. 



12. Filaments S-n n diam. 12. S. stagnatile. 



12. Filaments 12-18 M diam. 13. 6". subsecundum. 



13. Filaments 7-9 ,u diam. 9. S. aestivale. 



13. Filaments 4-6 M diam. 14. 6". minus. 



i. S. LUBRICUM (Dillw.) Kiitzing, 1845, p. 198; P. B.-A., 

 No. 866 ; 5". tenue var. lubricum Wolle, 1887, p. in ; Myxoncma 

 lubricum Hazen, 1902, p. 195, PI. XXVIII, figs, i and 2. 

 Tufts up to 30 cm. long, dark green, filaments much branched, 

 the branching principally of the opposite type, but often several 

 pairs, single branches or whorls arising from adjacent cells, 

 these cells being subglobose and smaller than other cells in the 

 same filament ; ramuli abundant, opposite, scattered, or near 

 the ends of the branches in more or less dense fascicles ; smaller 

 than the branches from which they arise, but only slightly if at 

 all tapering ; usually ending in a short point, but sometimes 

 setiferous; lower cells somewhat swollen, 14-17 /* diam., 2/3-2 

 diam. long, rarely more, with broad zonate chromatophore ; 

 ramuli 6-7 p. diam., cells about as long as broad. Fig. 84. 

 Ontario, Mass, to N. J., Alaska. Europe. 



The largest, and at least in the eastern states, the most com- 

 mon of our species ; all the species with prevailingly opposite 

 branching are grouped round this, resembling it in most charac- 

 ters, but with special developments on one or more lines. Like 

 most'of the species of Stigeoclonium it is a spring plant, inhabit- 

 ing clear running water. 



Var. varians (Hazen) nov. comb. ; Myxonema lubricum var. 

 varians Hazen, 1902, p. 198, PI. XXVIII, figs. 3 and 4 ; PI. 

 XXXIII, figs. 4 and 5 ; P. B.-A., No. 1075. Tufts short, not 

 exceeding 2 cm. ; filaments seldom over 12 ^ diam., cells 2-5 

 diam. long, with thin wall ; ramuli longer-pointed. Mass, to 

 New Jersey. 



