51 



Fig. 68. Achnanthes inflate , ( 5), cells 30-65H long, 10-l8|i wide, 

 X 1000. 



^ ) 



raphe -bearing valve 



rapheless valve 



Notes : 



Fig. 69. Achnanthes lanceolate , ( 5 ), cells 5-^Ou long, ^-lOu vide; 

 striae prominent, 13-17 in 10u; central area of rapheless 

 valve with horseshoe-shaped spot. X 1500. Common in 

 Great Lakes . 



o 



raphe -bear ing 

 valve 



rapheless 

 valve 



rapheless valve of 

 var. rostrate 



Notes : 



Fig. 70. Achnanthes minutissima , (5 ), cells 5- J +0u long, 2-k\x wide; 

 striae delicate, about 35 in lOu. Curved girdle view very 

 common. X 1500. Widely distributed. 



raphe -bearing 

 valve 



rapheless 

 valve 



girdle view 



Notes 



