T 



I he diatomaceous flora ol Finland has hitherto been the subject 

 J- of very few investigations. In the years 1838 and 1840 Ehren- 

 berg published an account of the diatoms in the diatomaceous 

 earths of Savitaipale and Kymmene gard, and in his large work 

 Microgeologie he has (on Plate XVII) figured the forms found by 

 him in these deposits. In some cases the figures are easy enough 

 to identify, but in many other cases this is almost impossible, as 

 the figures have been drawn to too small a scale and with too 

 little detail. From the deposit of Savitaipale Ehrenberg enume- 

 rates 59 and from Kymmene gard 47 forms, but these numbers 

 are subject to a considerable reduction, as in several instances 

 Ehrenberg has given specific names to mere varieties. For in- 

 stance, Eunotia robusta which occurs in Savitaipale deposit bears 

 not less than fifteen different names. 



In the year 1861 Nylander 1 ) published a list of the fossil 

 diatoms of Finland, based on the researches of de Brebisson, who 

 examined 10 samples of diatomaceous earth from different parts 

 of the country. The number of species, enumerated on this list 

 amounts to 130. 



The limits of the flora of Finland comprise also parts of the 

 large lake Ladoga, for which reason the researches of Weisse 2 ) 

 on the diatoms of Ladoga have to be considered in this work. 

 These researches, published 1864 and 1865, were unfortunately 

 carried out in the same manner as those of Ehrenberg, so that 

 the identification of the G2 species, enumerated and figured by 

 Weisse is in many cases impossible. 



l ) Xotiser ur Sallskap. pro Fauna et Flora Fennica Fdrh., 6:te haftet, 

 N. s. 3:dje haftet, pag. 145. 



•) Bull, ile l'Acad. de St. Petersbourg VIII, 21—25 and 3(19— 371. 



