vol.i] Setahell- Gardner. — Algce of Northwestern 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 C. saxatilis, since his G. arcta 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 lie determined with accuracy. 



Cladophora arcta f. conglutinata F. S. 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 plants some patent 

 lateral branches with acute terminal cells. 



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

 W.A.S., No. 5255x! ; near Dutch Harbor, Amaknak Island, Bay 

 of Unalaska, Alaska, E. G. McGregor, No. 5693!, W.A.8. and 

 A.A.L.. No. 4080!; Karluk, Kadiak Island, Alaska, TT.A.iS'., 

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

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

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

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

 (battered form). 



The typical G. arcta shows a flabellate 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. spinescens, but are not regularly 

 curved or circulate as in the latter. 



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

 nov. 



On mussels and algae, tide pools, upper litoral zone. West 



shore of Amaknak Island, Bay of Unalaska, Alaska, W.A.S. 



and A.A.L., No. 4002!, and in Collins, Holden and Setehell, 



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



Cladophora lanosa var. uncialis (Mueller) Thuret. 



On rocks, upper litoral zone. San Juan Island, Wash., 

 Tilden, No. 372! 



