Microplankton from the Finnish Waters dur ing the Month of May 1912. H 



It is a very donbtful case, as to whetlier we liave two species, intermediate forms 



ii»- as mentioned above. 



In the tables the two forms are separated from eacli other and noted as forma 



\ 





stations, 

 relation 



Fig. '25. Mesodinium rubrum. 



a. F. major. 



b. F. minor. 



950 

 1 



major and forma minor. The separation may be of some interest, if it shonld tum out 

 later, that we hâve two différent species. 



Mesodinium rubrum is rather common though not very nnmerous at all the 

 Frequently the smaller form is more numerons than the larger one, but the 

 between them can change from sample to sample at the same sta- 

 tion (F 61), and at station F 74 the larger form was the domi- 

 nating one. 



The maximum number of the smaller form was 4440 cells pr. ,Jfc 

 litre (station F 23, 5 mètres), while that of the larger was 2740 

 cells pr. litre (station F 61, 10 mètres). 



Tintinnopsis beroidea (Stein) Levander. 



(Fig. 26.) 





1867 Stein II, p. 154. 



1887 Daday, p. 547—548, pi. 19. 



1900 Levander, p. 18. 



Fig. 26. ' 



Tintinnopsis beroidea. 

 950 

 1 ' ■ 



The covering was formed as a narrow pitscher with acute base 



and a little drawn in opening. It was smaller than the following species (Tintinnopsis 

 tubulosa), the length was 53 ;<, the breadth 32 ;«. 



A few spécimens of this species occurred at stations F 61 and F 74. 



N:o 5. 



