A. CLEVE-EULER, DIAT. FLORA OF FINLAND. 5 



Hyalodiscus scoticus. C. {lacustris var.?) septentrio- 



Melosira Borreri. nalis. 



Coscinodiscus asteromphalus. 



Besides, some species, frequent in Li7onna-deposits, have 

 been met with in some of the marine gatherings from Knjäsha 

 in a few specimens only, and generally in the uppermost 

 part of the marine strata, where also some freshwater species, 

 such as for instance Cyclotella bodanica Eulenst., occur. I 

 therefore do not consider them as belonging to the genuine 

 marine-arctic association. They are: 



Nitzfichia punctata (W. Sm.) Campylodiscus Clypeus Ehb. 



Grun. C. Echineis Ehb. 



Surirella striatula Turp, 



There are to be noticed several cases of vicariating ex- 

 change between related forms in the association coming from 

 the Arctic Sea and that one, that arrived later with the 

 waters of the Litorina-Sea.. 



We thus find, among others, 

 only in the Arctic /Sea-deposits only in the deposits of the 



Litorina-Sea, 

 Diploneis SmitJiii var. per- Diploneis Smiihii var. rhom- 



magna.^ hica. 



Cocconeis speciosa. Cocconeis Pediculus. 



Achnanthes arctica. Achnanthes brevipes /. genuina. 



A. longipes. 

 Amphora Proteus. Amphora impressa. 



A. mexicana var. major. 

 A. robusta. 

 Coscinodiscus subtilis var. gla- Coscinodiscus balticus. 

 Cialis. 



As regards the marine-arctic diatoms, their development 

 in large and conspicuous forms seems to be a feature of 

 frequent occurrence, while on the contrary rather small, 

 sturdy forms are dominating in the remains from the Li- 

 torina-Sea. For instance Navicida latissima, N. Hennedyi, 



^ Concerning this and other new names, cfr the following, special 

 part of this paper. 



