Explanation of the plates I — VII. 

 Plate I. 



Fig. 1 — 3 Micrasterias decemdentatu (Nag) Arch. X sv) " i 



4 M. truncata (Corda) Breb. A monstrous semicell; the 

 other one was quite normal. [N:o 1109 b] < 530 , 

 5, 8, 11 M. truncata. Two cells from a sample which 

 was cultivated in a glass bottle several months. Origi- 

 nally most of the cells were quite normal, but gradually 

 the number of abnormal cells increased very considerably, 

 the lateral lobes not being subdivided in either of the se- 

 micells. Those individuals are almost identical with „M. 

 neodamensis Braun". Compare PI. Ill fig. 61—62. Fig. 



5 [N:o 1208 a]; fig. 8 [N:o 1221 a]; fig. 11 [N.o 1208 a]. 

 , 53 0/i 



„ 6 M. truncata var. semiradiata (Kiitz.) Cleve. From Wittr. 



6 Nordst. exs. n:o 373. X 530 , 



„ 7 M. truncata var. crenata (Breb.) Reinsch [N:o" 809 c] 



53 0/i 



„ 8 Vide fig. 5! 



„ 9 — 10 M. truncata var. quadrata Bulnh. 530 , 



„ 11 Vide fig. 5! 



12 M. radiata Hass., a monstrous semicell; the other was 

 normal. ,:! " , 

 „ 1 3 M. murrain West 530 , 



„ 14 M. quadridentata (Nordst.) Gronbl. From Wittr. & Nordst. 

 exsicc. n:o 371. 14 ■ a1 ,; U' 

 1") M. rotata (Grev.) Ralfs f. pseudoquadridcntata nova f. 



i 



