1920] Setchell^Crardner : Chlorophyceae 185 



3. Rhizoclonium Kerneri Stock. 



Filaments pale yellowish green, segments lO-14/i, diam., 3-7 diam- 

 eters long, free from rhizoids or branches. 



Growing in loose masses in tide-pools. Victoria, Vancouver Island, 

 British Columbia. 



Stockmayer, Ueber die Algengat. Rhizoclonium, 1890, p. 582 ; 

 Collins, Mar. Alg. Vancouver Island, 1913, p. 103. 



We have not seen any specimens of this species and are including 

 it upon the authority of Collins {loc. cit.). It is decidedly more slen- 

 der than the other four species of Rhizoclonium thus far detected on 

 our coast. 



4. Rhizoclonium lubricum S. and G. 



Plate 9, figs. 5a, b 



Filaments flaccid, lubricous, straight, cylindrical throughout, 3- 

 4.5 dm. long, pale green; segments 35-50/x, mostly 40/a diam., resting 

 segments 4-6 diam. long, after division segments 1-2 diam. long ; 

 chromatophore a coarse, parietal network ; pyrenoids small, numerous, 

 40-50 in resting segments; wall 2/* thick, homogeneous; rhizoids short, 

 mere prolongations of cells, non-septate, rare; zoospores and gametes 

 unknown. 



Growing attached in mud or floating on mud flats between tides. 

 Roche Harbor, Washington, and Berkeley and Alameda on the shores 

 of San Francisco Bay, California. 



Setchell and Gardner, in Gardner, New Pac. Coast Mar. Alg. IV,. 

 1919, p. 492, pi. 42, f. 5; Collins, Holden and Setchell, Phyc. Bor.- 

 Amer. (Exsicc), no. 2289. 



This form closely resembles R. riparium f. validum Foslie, but is 

 practically free from rhizoids, has thinner walls and larger and longer 

 segments. From R. implexum it differs in having broader, straigliter 

 filaments of very different consistency, as w^ll as, usually, longer seg- 

 ments. Unlike other species of Rhizoclonium it is very lubricous, in 

 mass, having the consistency of a Spirogyra. 



5. Rhizoclonium tortuosum (Dilhv.) Kuetz. 



Filaments rigid, crispate and contorted, dark green, 40-70/a diam., 

 forming woolly skeinlike or ropelike horizontal masses ; segments 1-2, 

 up to 6 times as long as broad, wall thick, indistinctly lamellose ; 

 rhizoids short, few or, more usually, none. 



