178 SAUNDERS [414] 



Filaments dark green, attached at base, 300-500 [i in diameter ; cells 

 ij4 to 3 times as long as broad. 



A large and rather coarse species, abundant throughout the whole 

 Arctic region, and as far south as the cold currents extend in the At- 

 lantic and the Pacific. 



Rhizoclonium riparium implexum (Dillw.) Rosenvinge. 



Yakutat Bay (192), floating in large flocculent masses. 



Rather light green in color ; filaments 20-30 (i in diameter ; cells i 

 to 5 times as long as broad. 



In these specimens the filaments reach a diameter of 30 /i ; the cells 

 are sometimes five times as long as broad. No rhizoidal branches were 

 noted, thus placing the form as variety implexum. It is difficult to 

 distinguish this variety technically from species of Chcetomorfha^ but 

 all forms of Rhizoclonium have a certain irregularity in form of the 

 cells, which is readily recognized when one becomes familiar with 

 these plants. 



Cladophora arctica (Dillw.) Kuetz. 



Glacier Bay (91) ; Ocean Cape, entrance to Yakutat Bay, on rocks 

 (233) ; near Sand Point, Popof Island (381). 



Filaments 40—90/^ in diameter, straight and rather stiff; branches 

 erect ; basal parts, especially in older plants, emitting numerous slender 

 rhizoidal descending filaments, by which the whole tuft is matted to- 

 gether. 



Cladophora scopaeformis (Rupr.) Harv. 



Yakutat Bay (225) ; Sitka, on exposed rocky points (185) ; Kukak 

 Bay (320, 327), on rocks exposed to direct washing of the waves. 



Filaments 100-200 11 in diameter, straight and stiff ; branches erect, 

 all but the youngest parts attached to each other by short hooked 

 branches, forming long, simple or branching, slender tufts, from 2 to 

 10 mm. in diameter. 



This is a characteristic species of the coast from California north- 

 ward, resembling a larger and coarser C. arctica in its later stages. 



Cladophora flexuosa (Griff.) Harv. 



Filaments pale green, flexuous, sparingly branched, 20-60 11 in di- 

 ameter ; cells 2 to 3 times as long as broad ; ultimate ramuli short, 

 curved, usually secund. 



The determination of these specimens Is based on their resemblance 

 to No. 206. Alg. Am.-Bor. Exsicc, The species is found on both 



