394 Univcrsify of California Puhlications in Botany [Vui,. 7 



material examined to be like those figured by Saunders. His figures 

 sliow tlh' main filaments as being like those of all the known Sfrehlo- 

 nrmas, monosiphonous, while those in both collections of material which 

 we have examined are uniformly polysiphonous, that is, the cells of the 

 main central parts of the thallus are all divided once or twice length- 

 wise. This never takes place in the plants which bear gametangia and 

 which are intimately associated with them. 



The measurements, method of branching of the two sets of plants, 

 and tlu'ir chromatophore characters are practically the same. At 

 least two interpretations of this polysiphonous phenomenon appeal to 

 us. They may represent a polymorphic state, in which a nonsexual 

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

 unique condition in the genus Strehlonema, or the polysiphonous con- 

 dition of the main filaments, found only in the nonsexual plants, may 

 represent 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 Strehloncma. We 

 have amended the family Ectocarpaceae to include species with this 

 poh'siphonous condition. 



Streblonema Johnstonae sp. nov. 



Plate 43, figure 4 



Frondibus microscopicis ; filamentis repentibus moderate ramosis. 

 ramis alternis aut oppositis, raro leviter secundis ; filamentis erectis 

 plerumque simplicibus, apice basimque leviter attenuatis, supra super- 

 ficiem hospitis extendentibus, pro parte, brevi-pilif eris ; cellulis fila- 

 mentorum primariorum repentium forma plus minusve variabilibus, 

 plerumque doliiformibus, 12-18/ji diam., 2.5-5-plo longioribus; cellulis 

 filamentorum erectorum pro parte latissima usque ad 24/a diam., fere 

 cylindricis, ad dissepimenta constrictis ; chromatophoris tenuibus, 

 parietalibus. in cellula quaque singulis, parietes cellularum fere 

 tegentibus; zoosporangiis ignotis; gametangiis conicis usque ad in- 

 aequaliter fusiformibus, 90-130/x longis, 28-36/j, latis, plerumque brevi- 

 pedicellatis in filamentis prope superficiem hospitis repentibus positis. 



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

 with Streblonema corymhiferum and S. anomalum. San Pedro, Cali- 

 fornia. Type, Mrs. H. D. Johnston, no. 115c (Herb. Univ. Calif., 

 no. 04663), August. 



Of the three plants found ramifying among the filaments of the 

 host mentioned above, Strehlonema Johnstonae is the most robust in all 



