424 University of California Publications in Botany [Vol. 8 



13. Ectocarpus commensalis S. and G. 



Fronds 200-400/* hig-h, densely fasciculate, attached by inter- 

 twined, slightly branched rhizoids penetrating among the utricles and 

 even well among the medullary filaments of the host ; erect filaments 

 alternately branched near the base, simple above, slightly attenuated 

 upward, not piliferous; cells of the erect filaments cylindrical, not 

 constricted, 12-18/* diameter at the base of the filaments, 1.5-2.5 times 

 as long as the diameter ; chromatophores band-shaped, few in each 

 cell ; zoosporangia unknown ; gametangia blunt-fusiform to cylindrico- 

 conical, short-pedicellate, mostly lateral near the base of the filaments, 

 rarely terminal, GO-lOO/i long, 15-20/i wide. 



Growing on Codiiom Setchellii Gardner, Carmel Bay, and on 

 C odium fragile (Suring.) Hariot, Pacific Grove, Monterey County, 

 California. 



Setchell and Gardner, Phyc. Cont. VI, 1922, p. 407, pi. 48, figs. 

 32-35. 



This minute species of Ectocarpus is one of .several occurring on 

 species of Codium, both on this coast and on that of southwestern 

 Europe. The colorless rhizoidal filaments descend into the substance 

 of the host even to the central (or basal) medullary tissues. The 

 smaller diameter of the erect filaments and the more narrowly conical 

 or fusiform gametangia readily distinguish this species from the 

 others. 



14. Ectocarpus eramosus S. and G. 



Fronds diffused or in diminutive tufts, 1-3 mm. high, attached by 

 irregularly branched rhizoidal filaments penetrating deeply among the 

 utricles of the host ; erect filaments eramose or rarely producing short, 

 divergent branches usually terminated in gametangia, slightly atten- 

 uated toward the base and the apex, not piliferous; cells of mature 

 filaments 28-40/i diam., 0.5-1.25 times as long as the diameter, cylin- 

 drical, very slightly constricted ; chromatophores relatively thick, 

 closely crowded, irregular bands without pyrenoids; zoosporangia 

 unknown ; gametangia very variable in shape and size, lateral and 

 alternate along the entire filament or occasionally terminal and seriate 

 on the main filaments, mostly on few-celled pedicels, lateral forms 

 cylindrical to cylindrico-conical, 150-230/i long, 26-36/t diam., ter- 

 minal, seriate forms, 700-900/i long, 15-20/* broad. 



