FRESHWATER ALGÆ FROM TUDDAL IN TELEMARK. 183 



237. Staurastrum Avicula. Ralfs. 

 Rare. 



238. Staurastrum OpMura. Lund. 

 Lundell: Desniid. Sueciæ. Tab. iv. 



Not very uncommon, in quantity in a single sample. 

 Addenda. 



239. Staurastrum megacanthum. Lund. 

 Very rare. 



240. Staurastrum jaculiferum. W. West. 

 W. West: Freshw. Algae. W. Ireland. PI. xxii. 

 In quantity in a single sample. 



241. Staurastrutn furcigerum. Breb. 

 Rare, in a single sample. 



Genus Sphcerososma. Corda 1835. 



242. Sphærozosma excavatum. Ralfs. 

 Somewhat scarce. 



243. Sphærozosma granulatum. Roy & Bissett. 

 General, and often in quantity. PI. Ill, Fig. 15. 



Genus Spondylosium. Breb. 1844. 



244. Spondylosium secedens. De Bary. 



W 6cG.S. West. Freshw. Algæ. N. Ireland. PI. ii. 

 Rare, only from a single locality. 



245. ? Spondylosium planum. (Wolle) W. & G. S. West. 

 Only observed in a single specimen. Spondylosium planum 



is a frequent constituent of the Norwegian freshwater plankton. 



Genus Hyalotheca. Ehrbg. 1841. 



246. Hyalotheca dissiliens. (Dillw.) Ehrbg. 

 General. 



247. Hyalotheca mucosa. (Dillw.) Ehrbg. 

 Somewhat rare. 



