444 University of California Publications in Botany L VoL - 8 



to us. They may represent a polymorphic state, in which a non-sexual 

 plant differs in form from a sexual plant of the same species, a unique 

 condition in the genus Streblonema, or the polysiphonous condition 

 of the main filaments, found only in the non-sexual plants, may repre- 

 sent a character belonging to a wholly different genus, and hence it is 

 a new species of that genus. Until a more extensive study of fresh 

 material can be made, we feel that it is best to take the former view, 

 and place it in a new and polymorphic species of Streblonema. We 

 have amended the family Ectocarpaceae to include species with this 

 polysiphonous condition. 



3. Streblonema Johnstonae S. and G. 



Plate 52, fig. 4 



Fronds microscopic ; creeping filaments moderately branched, 

 branches alternate or opposite, at times slightly secund ; erect filaments 

 mostly simple, tapering slightly upward and at the base, extending 

 beyond the surface of the host, in part short-pilif erous ; cells of the 

 main creeping filaments more or less irregular in shape, chiefly doli- 

 iform, 12-18/a diam., 1.5-5 times as long ; cells of erect filaments up to 

 24/A diam. in the widest part, nearly cylindrical, constricted at the 

 cross-walls; chromatophore a thin parietal band, nearly covering the 

 cell ; zoosporangia unknown ; gametangia cone-shaped to unsym- 

 metrically fusiform, 90-130^ long, 28-36/t broad, mostly short-pedicel- 

 late on the creeping filaments extending to the surface of the host. 



Growing in Cumagloia AnolersonU (Farlow) S. and G. in company 

 with Streblonema corymbiferum and 8. anotnalum. San Pedro, 

 California. 



Setchell and Gardner, Phyc. Cont. V, 1922, p. 394, pi. 43, fig. 4. 



Of the three plants found ramifying among the filaments of the 

 above mentioned host, Streblonema Johnstonae is the most robust in 

 all of its parts. It can readily be distinguished from the other two 

 species with which it is associated by the large size of the gametangia. 

 No zoosporangia have been observed. 



4. Streblonema vorax S. and G. 



Fronds microscopic, prostrate filaments profusely branched, very 

 tortuous, penetrating among the epidermal cells and spreading into 

 the interior of the host, decomposing the walls and filling the large 



