396 Univrrsil!/ of California I'ublicaiions in Botany [Vol.7 



lifts up llic surfnci' layer oi" cells of the host, forming a small blister 

 which finall\ ruptures, as in the case of Rosenvinge's plants. The 

 erect filaments are almost simultaneously transformed into gametangia, 

 exeej)! a few in llic center which develop into hairs. 



P^slie (1894. j). 167, 23 in reprint) describes forms of the same 

 species found growing on Laminaria saccharina at Kjelvik and at 

 Lyngii near Tronis0, Norway. These he listed under Ectocarpus 

 (Strcblonema) accicUoides Rosen vinge. The measurements of the 

 parts of his forms average, in general, a little larger than those of 

 Rosenvinge. De-Toni (1895, p. 577) cites these Arctic plants under 

 Strcblonema aecidioides Rosenv. Foslie gives 80/i, as the extreme 

 length of the gametangia. 



Streblonema investiens (Collins) comb. nov. 



Fronds occupying indefinite areas on the host ; creeping filaments 

 irregularly branched, often curvdng outward and bearing on the out- 

 side short, simple, or sparsely branched filaments ; hairs sparse ; cells 

 of creeping filaments o-S/x diam., 1-2 (up to 4) times as long, swollen, 

 or cylindrical; cells of . the ramuli Gfi diam., 1-2 times as long; cells 

 of the hairs S/x diam. ; chromatophores discoid, small, several in a cell ; 

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

 filaments and the ramuli, 20/x long, 15fx broad ; gametangia cylindrical, 

 25-40/A long. 8-1 0/i, broad; loculi mostly uniseriate, gametangia and 

 zoosporangia growing on the same plant. 



Growing in the fronds of HelmintJiocladia calvadosii (Lamour.) 

 Setchell. San Pedro, California. July. 



Strepsithalia investiens Collins, in Collins, Holden, and Setchell, 

 Phyc. Bor.-Amer. (Exsicc), no. 738, 



It seems that the chief distinction between the genera Strepsithalia 

 Sauvageau and Streblonema Derb. and Sol. is the secretion by Strepsi- 

 thalia 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 Streblonema. 



