BTHANG TILL K. SV. VET.-AKAD. HANDL. BAND 24. AFD. III. N:0 2. 23 



It will be seen from tliis list tliat a great many forms 

 of freqiient ocourrence oii the continent of Europé are want- 

 ing or occur sparingly only. The genera, of whieh few or 

 no species are found, are ^ 



Gyrosigma, 



Pleurosigma, 



Cocconeis, 



Epithemia, 



Cymatopleiira, 



Surirella, 



Campylodiscus. 



But on the other hand there is a considerable diiferenoe 

 between the diatomaceoiis flora of Lappland and of Spitz- 

 bergeii^Franz Josef Land. In the former region the number 

 of forms amount to about 300 and in the latter to about 

 150. Common to both are 78 forms or 55 percent of the 

 diatoms from Spitzbergen and Franz Josef Land, but 26 per- 

 cent only of the diatoms of Lappland. In the last named 

 region the genera Eiinotia, CywheUa, Frustulia, Tahellaria, 

 Pinmilaria and Gomphonema occur in a great number of 

 individuals and in a very great profusion of forras, but in 

 Spitzbergen and Franz Josef Land they are of far less im- 

 portance. 



^ See A. Cleve 1. v. p. 38. 



