THE ALG^ 415 



sides of the Atlantic, but appears not to have been previously reported 

 from the Pacific. 



The following specimens of Cladophora can be noted by numbers 

 only, specific determination being impracticable at present. 



Annette Island (17, 45, 48); Wrangell (56); on rocks, Glacier 

 Bay {^^(i^ ; forming masses on rocks, Sitka (157) ; on protected side 

 of exposed rocks, Virgin Bay, Prince William Sound (295). 



Family GOMONTIACB^^. 



Gomontia polyrhiza (Lagerh.) Born. & Flah. 



Popof Island. 



Basal layer growing in the substance of marine shells, erect filaments 

 extending to the surface, zoospores formed in sporangia. 



Family DERBESIA CE.^. 



Derbesia vaucheriaeformis (Harv.) J. Ag. 



On a sponge in Yakutat Bay (234). 



Filaments 30-40 it in diameter, simple below, dichotomous above, 

 branches patent, 20-30 11 wide, often with a cuboidal cell near the 

 base; zoosporangia ovoid or pyriform, 140-200 by 50-80 /z, short-pedi- 

 celled. 



As there are no mature spores on this specimen, there is a possible 

 doubt as to the identification, but the characters agree well with the 

 species named. 



Derbesia marina (Lyng.) Kjellm. 



Sitka, in quiet water (149). 



Filaments 50-60 /;t in diameter at the thickest, tapering slightly; 

 sparingly branched laterally, usually two partitions found at the base 

 of each branch, enclosing a short cell; zoosporangia 150-180 by 90— 

 120 /i, short pediclled. 



Family VA UCHERIA CEyE. 



Vaucheria sessilis (Vauch.) DC. 



On an overhanging dripping cliff, Juneau (74). 



Filaments up to 70 11 in diameter ; oogonia usually two or three to- 

 gether, sessile, ovate or ovate-oblong, about 60-150 ,u, beaked ; anther- 

 idia in the vicinity of the oogonia, formed at the end of a short, hooked 

 or curved ramulus. 



With antheridia and oosfonia. 



