FRESHWATER ALGÆ FROM TUDDAL IN TELEMARK. 165 



81. Closterium subulatum. (Kütz.) Breb. 

 Very rare. 



82. Closterium Kuetzingii. Breb. 



In two samples. Size: long. 460 u, lat. 17 ,«. 



83. Closterium rostratum. Ehrbg. 

 Somewhat scarce. 



83 a. var. hrevirostratum. W. West. 

 Very rare. 



Genus Docidium. Breb. 1844. em. Lundell 1871. 



84. Docidium Baculum. Breb. 

 Very scarce. 



85. Docidium undulatum. Bail. 



This rare species occurred in a single sample. The semi- 

 cells were only 8 plicate at the base. Size: long. 230 f^, lat. 

 max. 16,5 u. PI. IV, Figs. 15 & 16. 



Genus Pleurotœnium. Näg. 1849. 



86. Pleurotœnium Trabecula. (Ehrbg.) Näg. 

 General, but somewhat scarce. 



87. Pleurotœnium Ehrenbergii. (Breb.) De Bary. 

 Scarce, only in few samples. 



Genus Tetmsmorus. Ralfs 1844. 



88. Tetmemorus Brehissonii. (Menegh.) Ralfs. 

 Scarce. The var. minor was much more frequent. 



88 a. var. minor. De Bary. 



General, but usually not in quantity. Size : long. 65 & 66 ju, 

 Jat. 17 & 17,5 1.1, lat. isthm. 12,5 & 13,5 ^. Pl. IV, Fig. 2. 



89. Tetmemorus granulatus (Breb.) Ralfs. 



Frequent, and often in great abundance. Up to 4100 feet. 



89 a. var. attenuatus. W. West. 



Rare, only in a few samples, and never in quantity. 



