73 



Fig. 112. Navicula contents , (5), cells 5-15H long, 2-3n wide. 



X 1500. May reach high numbers in southeastern brackish- 

 water stations. 



valve views 





' Ill lll ff 



N. contenta 



form parallela form biceps 



Notes 



Fig. 113. Navicula cryptocephala , (5), cells 20-^0u long, 5-7U 

 wide; striae fine, 16-18 in 10u. X 1000. 



valve views 



N. cryptocephala 

 Notes : 



var. veneta 



var. intermedia 



