ÖFVERSIGT AF K. VETENSK.-AKAD. FÖRHANDLINGAR 1899, N:0 8. 831 



Infusorians: 



Tintinnopsis lacustris Entz. + . 

 Flagellates: 



Dinohryon sertularia Ehb., cc. 

 Diatoms : 



Asterionella formosa v. sahtilis Grun., r. 



Tahellaria fenestrata (Lyngb.) Kütz., r. 



» » v. geniculata n. var., r. 



Frustules with a geniculate, lateral flexion in the niiddle, both 

 ends of the diatom thus making an angie of about 120°. Indi- 

 viduals disposed in radiale aggregrates, sonietimes forniing two 

 superposed spiral turns (figg. 1, 2). Length of the valve 0,1 mm., 

 breadtli of tlie valve, where not dilated, 0,004 mm. The central 

 part of the valve has a most variable shape (figg. 3, 4, 5). In 

 the best marked forms it is prolonged on the outer side into a 

 kind of crest. 



This new variety is a well oQtfit floating-form of T. 

 fenestrata. A number of individuals keep together by tlie corners, 



Öfvers. af K. Vet.-Ahad Förli. 1899. Årg. 56. N:o 8. 4 



