63 



Fig. 92. Frustulia vulgaris , (5), cells 30-70u long, 10-13" wide. 

 X 1000. 



^ •"•'•'i'ilr'i-niii 



valve view 

 var. capitata 



Notes : 



26a Valves with longitudinal "shadow"-lines or blank spaces 27 



26b Valves without longitudinal lines or blank spaces 29 



27a Transverse striae continuous, crossed by one or two 



longitudinal "shadow "-lines paralleling valve margin - CALONEIS 



Fig. 93. Caloneis amphisbaena , (5), cells 36-8OU long, 20-30u wide. 

 X 1000. Common in the Rio Grande River. 



valve view 



Notes : 



Fig. 9k. Caloneis bac ilium , (5), cells 15-^5n long, k-9v wide; 

 can be mistaken for Stauroneis sp. X 1000. 



valve view 



Notes : 



