1925] SetchfU-Gardnrr: Melnnophyceae 463 



9. Myrionema foecundum f. majus S. and G. 



Fronds forming circular cushions, 1-2 mm. diam. with convex 

 upper surface; prostrate portion composed of closely adhering, regu- 

 larly radiating filaments ; erect filaments densely crowded, unbranched ; 

 cells C3'lindrical, 5-7/^ diam. ; true hairs sparse, distributed promiscu- 

 ously over the frond, meristem at the base, surrounded by a sheath, 

 400-500/x long, cells 6/* diam., 5-8 times as long as the diameter at 

 the apices; "ascocysts" sessile on the prostrate filaments, cylindrical, 

 slightly larger at the distal end, 45-55/i, long, 8-12/i, diam., scattered 

 sparsely over the frond, occasionally in groups; zoosporangia un- 

 known ; gametangia sessile on the basal filaments, cylindrical, 60-80/a 

 long, 6-Six diam., arising by transformation of all of each erect 

 filament, cross-walls horizontal or oblique. 



Growing on Laminaria ephemera Setchell. Port Renfrew, Van- 

 couver Island, Neah Bay, Puget Sound and central California (Carmel 

 Bay). 



Setchell and Gardner, Phyc. Cont. II, 1922, p. 338, pi. 32, fig. 7. 



This small epiphyte seems to be restricted in its habitat to the 

 above named host. The only known localities in which the host has 

 been observed are those mentioned above. The material from each 

 locality is richly infested by this epiphyte. The host, richly infested, 

 was distributed by Miss Josephine Tilden in her American Algae 

 (Exsicc), no. 609, under Renfrewia parvula Griggs. 



It seems very closely related to Myrionema foecundum f. simpJi- 

 cissimum. The differences are in the larger measurements of all of 

 the parts, the presence of numerous, larger, so-called "ascocysts, " 

 occurring in groups, or scattered among the gametangia, in the 

 presence of well-developed hairs, and in the more convex upper 

 surface of the mass of erect filaments. 



10. Myrionema foecundum f. divergens S. and G. 



Plate 55, figs. 8, 9 



Fronds forming circular cushions, 1.5-3.5 mm. diam. ; basal por- 

 tion composed of regularly radiating filaments closely compacted, 

 firmly adhering to each other and to the host ; sterile erect filaments 

 sparse, unbranched, blunt, scattered promiscuously among the game- 

 tangia, 300-400/A long; true hairs absent; "ascocysts" numerous, 

 scattered among and shorter than the gametangia, cylindrical to 

 clavate ; cells of the creeping filaments 5-6ju, diam., 1.5-2 times as 



