Vol. ]j Setchell- Gardner. — Alga' of Northivesfern America. 225 



Mr. Collins has made all the determinations quoted except, 

 of course, those of Harvey. Harvey's specimens may belong- 

 rather under G. scopceformis or G. saxatilis, since his G. (itrta is 

 of the older and broader conception. Mr. Collins also notes that 

 Miss Tilden's G. arcta (No. 373) can belong to this species only 

 in its very broadest sense, but that the specimens distributed 

 are not good enough to ])e determined with accuracy-. 



Cladophora arcta f. conglutinata F. 8. Collins f. nov. 



Filaments adhering in drying into pointed tufts; descending 

 rhizoids plentiful. In addition to the regular, erect, blunt 

 branches, there are at the base of the older i)lants some patent 

 lateral branches with acute terminal cells. 



On stones and rocks, litoral zone. St. Michael, Alaska, 

 ir..-l..V., No. .525r)x! ; near Dutch Harbor, Amaknak Island, Bay 

 of Unalaska, Alaska, B. G. McGregor, No. 5693!, W.A.S. and 

 A.A.L., No. 40H()!; Karluk, Kadiak Island, Alaska, ir.A.»S'., 

 Nos. 5068!, 5069!; Uyak Bay, Kadiak Island, Alaska, W.A.^S. 

 and A.A.L., No. 5086!; Esquimalt, B. C, N.L.G., No. 329!; 

 Channel Rocks, west of Seattle, Wash., X.L.G., No. 356!; 

 near Deer Harbor, San Juan Island, Wash., X.L.G., No. 202! 

 (battered form) . 



The typical G. arda shows a fiabellate or nearly circular outline 

 in the mounted specimen, the individual filaments being quite free. 

 The present form has quite a different habit, the filaments uniting 

 in tufts like a magnified Symploca. The acute lateral branches 

 show a tendency toward G. spinesceiis, l)ut are not regularly 

 curved or circinate as in the latter. 



Cladophora arcta f. pulvinata (Foslie) F. S. Collins comb. 



nov. 



On mussels and algw, tide ])ools, ui)per litoral zone. West 

 shore of Amaknak Island, Bay of Unalaska, Alaska, H'.A.N. 

 and A.A.L., No. 4002!, and m Collins. Holden and Setchell, 

 P. B.-A., No. 918! Determined by F. S. Collins. 



Cladophora lanosa var. uncialis (Mueller) Thurot. 



On rocks, ui)pei- litoi-al zone. San •luaii Island, Wash., 

 Tildf),, No. 372! 



