182 KAARE MÜNSTER STRØM. 



229. Staurastrum heæacerum. (Ehrbg.) Wittr. 

 Scarce. 



230. Staurastrum crenulatum. Del p. 

 Rare. 



231. Staurastrum prohoscideum. Arch. 

 Scarce. 



232. Staurastrum gracile. Ralf.s. 

 General, but never in great abundance. 



233. Staurastrum paradoxum^. Meyen. 

 Common. 



233 a. var. longipes. Nordst. 



This variety, which is chiefly confined to the plankton 

 was rare. 



234. Staurastrum, vestitiim. Ralfs. 

 In two or three samples. 



235. Staurastrum Manfeldtii. Delp. 



W. & G. S. West: Freshw. Algæ. Orkney & Shetland. PI. ii. 

 Scarce. 



236. Staurastrum controversum. Breb. 

 forma elegantior. 



The form observed differed conspicuously from the type, 

 and also from all the varieties 1 have seen." Lütkemüller 

 gives a good account of the species. (Desmid. Millstättersees. 

 p. 20 & 21.) 



The form from Tuddal differs from the type in being 

 pentaradiate with slender processes, with four spines on each. 

 The spines which cover the processes are very much slender 

 and elegant, and also shorter. I think that Lütkemüller on 

 his drawings has failed to depict the small reduced spines which 

 are situated between the processes. There is no reason to make 

 a variety of this form as St. controversum is so variable, and 

 so little is known about the variation of the species. 



This beautiful form occurred at a single locality. PI. Ill, Fig. 13. 



