58 



Fig. 81. Cymbella cistula , (5), cells 35-l80u long, 15-36n wide; 

 6-9 striae in lOu; two or more prominant punctae in the 

 central area. X 1000. 



valve view 



Notes 



Fig. 82. Cymbella mexicanum , (l), cells 50-100u long, 20-^On wide; 

 central area with a prominant puncta; similar to C. 

 tumida, but striae have coarser punctae. X 800. 



valve view 



Notes : 



Fig. 83. Cymbella prostrata, (5), cells 20-100u long, 10- 30u wide; 

 7-10 striae in lOu. X 1000. 



valve view 



Notes : 



