400 SAUNDERS 



The plant forms minute, hard, dark bkiish green thalli 1-3 mm. in 

 diameter, which finally become agglutinated into hollow indefinite 

 masses. 



Family HTDR URA CE.^. 



Hydrurus penicillatus Ag. 



Plant forming dark olive-green filaments attached to smooth round 

 pebbles in a rapid brook emptying into Kukak Bav (351). 



The filaments are 7—20 mm. in length, having long primary branches 

 bearing many short penicillate ones. 



CONJUGATE. 

 Family DESMIDIACE^^. 



Mesotaenium braunii De Bary. (Plate xliii, fig. 39.) 



In a freshwater pond near Cook Inlet. 



The cells are cylindrical, 2^^ times as long as broad; 16 to iS/^ 

 broad, 38-4:^ ,a long. 



Penium interruptum Breb. 



In a freshwater pond near Seldovia, Cook Inlet. 



Plant 24-40// wide, 130-145// long. Slightly smaller in all its di- 

 mensions but agrees otherwise with the description. 



Penium closterioides Ralfs. 



In a freshwater pond on Popof Island. 

 Diameter 140//, length i^o//. 



Penium margaritaceum (Ehrenb.) Br^b. 

 Occasional in freshwater, Kukak Bay. 

 Cells 25 // wide, 100 // long. 



Penium polymorphum Pcrty. 

 In quiet water near Kukak Bay. 

 Cells 22 // wide, 35 // long. Very delicately punctate-striate. 



Penium oblongum De Bary. 



In a freshwater pond near Virgin Bay, Prince William Sound 

 (302). 



Diameter 21 //., length 64//. 



Penium digitus (Ehrenb.) Breb. (Plate xliv, fig. 3.) 

 In quiet water, Virgin Bay. Rare. 

 Diameter 54/i, length 1S3/7.. The plant averages almost a third 



