ko 



Fig. 1*7. Fragilaria construens, ( 5 ), cells 7-25u long, 5-12u wide; 

 striae delicate, 1^-17 in 10n; pseudorapne broader in 

 central region. X 1000. Abundant in northern waters. 



valve view 



girdle view 



var . subsalina 



S V l'l V . S '.S-^-, .■■'^.'.Wr V J.'-V. 



girdle view 



^TTTMIII'lllllllUIIIIUMIIIlllll 



Notes : 



valve view 



Fig. 1*8. Fragilaria crotonensis , (3,5), cells l*0-150n long, 2-3u wide; 

 15-18 striae in 10|X. X 1000. Widely distributed. 



Notes 



girdle view 



11 ■ IHWIHUii.ii 1 u„. 



-—"""■" ■ m^mi 



valve view 



-p j^.j H 1 1 iff* 



Fig. 1*9. Fragilaria inflata , (12), cells l8-50u long, 6-10n wide, 

 X 1200. In Great Lakes. 



— -^^^^ 



valve 

 view 



girdle 

 view 



Notes : 



