464 Universitij of California Puhlicaiions in Botany ['^''ol. 8 



long"; cells of the erect filaments 8-9/t diam., 1.5-3 times as long, 

 cylindrical, not constricted; zoosporangia unknown; g:ametangia 

 variable in shape, cylindrical, clindrico-conical or fusiform, 50-60/a 

 long', 7.5-8. 5/A broad; loculi 1-2-seriate, 



Growing on the sporophylls of Nereocystis Luetkeana. Pacific 

 Grove, California. 



Setchell and Gardner, Phyc. Cont. II, 1922, p. 338, pi. 34, figs. 8, 9. 



This form of 31. foecundum manifests some slight differentiations 

 not present in any other form of the species. Scattered promiscuously 

 over the fronds are erect filaments two to three times as long as the 

 gametangia. The "ascocysts" are abundant. Some irregularities 

 are also shown in the creeping filaments. Typically the branching 

 seems to take place by the splitting of the apical cell, but it seems 

 that frequently one of the dichotomy fails to develop till later, pro- 

 ducing the appearance of lateral branching. There is also an occa- 

 sional oblique or longitudinal division of a cell of the creeping fila- 

 ments perpendicular to the host. 



11. Myrionema minutissimum S. and G. 



Plate 55, figs. 1-3 



Fronds forming inconspicuous cushions, 0.75-1.5 mm. diam. ; pros- 

 trate portion composed of very closely compact regularly radiating 

 filaments; erect filaments densely crowded, cylindrical, all fructi- 

 ferous; true hairs unknown; cells of creeping filaments 4/x diam., 

 quadrate in the center of the frond, slightly longer at the margin ; cells 

 of erect filaments the same in size as in the creeping filaments ; zoo- 

 sporangia and "ascocysts" unknown; gametangia on 4-8-celled 

 pedicels, cylindrical, densely crowded, 34-40/x long, 4-4.5;a broad. 



Growing on the cysts of Egregia Menziesii. Cast ashore near the 

 "Cliff House," San Francisco, California. 



Setchell and Gardner, Phyc. Cont. II, 1922, p. 336, pi. 34, figs. 1-3. 



Myrionema minutissimum may be distinguished by the absence of 

 sterile erect filaments and hairs, and by the small sized, very densely 

 crowded pedicellate gametangia. Thus far no "ascocysts" nor zoo- 

 sporangia have been observed. In its phylogenetic relationship it 

 would seem to stand equally close to M. corunnae and 31. foecundum, 

 differing from each, however, in details of measurements. The erect 

 filaments are of the same diameter at their bases as the length of the 

 cells in the creeping filaments. Since the lower part of each remains 

 sterile, it gives the mass of cells the appearance of being parenchy- 

 matous. 



