91 



Fig. 3A5. Nitzschla apiculata, (5), cells 20-50|i long, 5-8u wide; 

 differs from N. hungarica by having indistinct carina! 

 dots; about 17-20 striae in lOu. X 1000. Common in 

 the Arkansas River. 



valve view 



Notes : 



Fig. lh-6. Nitzschia denticula , (5), cells 10-100u long, 3~8u wide; 

 carinal dots rib-like and extended, 5-8 in lOu; 14-20 

 striae in lOu. X 1000. In southwest. 



valve view 



Notes 



Fig. IV7. Nitzschia dissipata , (5), cells 15-70u long, k-Jv wide; 



keel slightly eccentric, 6-8 carinal dots in lOu; striae 

 indistinct. X 1000. 



valve view 



Notes : 



