1925] Setchfll-Gardnrr: Melanophyceae 453 



cell; zoosporangia ovoid, sessile or on 1-celled pedicels on both the 

 creeping filaments and the ramuli, 20/x long, 15/1, broad ; gametangia 

 cylindrical, 25-40/x long, 8-lOjU, broad ; loculi mostly uniseriate ; game- 

 tangia and zoosporangia growing on the same plant. 



Growing in the fronds of Helmmthodadia calvadosii (Lamour.) 

 Setchell. San Pedro, California. 



Setchell and Gardner, Phyc. Cont. V, 1922, p. 396. Strep^thalia 

 investieiis Collins, in Collins, Ilolden and Setchell, Phyc. Bor.-Amer. 

 (Exsicc), no. 738. 



It seems that the chief technical distinction between the genera 

 Strepsithalia Saiivageau and Strehloiiema Derb. and Sol. is the secre- 

 tion by Strepsithalia of a rather copious gelatinous sheath investing 

 the entire plant, particularly the exposed portions, the ramuli. Since 

 we are not able to demonstrate the presence of such a sheath, even to 

 the slightest degree, we have thought it best to place Collins' 

 Strepsithalia investiens in the genus StreMonema. 



FAMILY 3. MYEIONEMATACEAE foslif. (orthog. mut.) 



Thallus two-fold, viz., (1) of a prostrate disk formed of radiating 

 filaments more or less closely united and one or two cells in thick- 

 ness, entirely superficial or penetrating the host by short rhizoidal 

 filaments, and (2) of erect, simple or branched, monosiphonous, 

 usually parallel filaments, either free or enclosed in a common jelly ; 

 growth peripheral in t'he basal portion and subapical or intercalary 

 in the erect filaments ; hairs present or absent ; erect filaments entirely 

 fertile, partially sterile or sterile and fertile intermixed ; cells uninu- 

 cleate, each with one or more parietal disk-shaped or band-shaped 

 chromatophores ; zoosporangia unilocular, terminal or lateral, sessile 

 or pedicelled, never intercalary; gametangia plurilocular, terminal or 

 lateral, with loculi uni- or pluriseriate ; gametophyte and sporophyte 

 identical in size and structure. 



Myrionemaceae Foslie, Contr. Knowl. Mar. Algae Norway, I, 1890, 

 p. 91. 



The members of the Myrionemataceae, as we understand them, 

 seem closely related to the Ectocarpaceae, on the one hand, and the 

 Elachisteaceae on the other. There seems to be little reason for plac- 

 ing the genera in Chordariaceae as Kjellman (1893, p. 225) has done, 

 nor even associating them closely with the Mesogloiaceae, as Oltmanns 

 (1922, p. 29) has done, since it seems to us that Strepsithalia, in 

 typical form, resembles StrehJonema in its basal portion, but agrees 



