24 EXPLANATION OF THE PLATES. 



Fig. 11. Gyrosigma Hippocampa : a, front view ; b, side 

 view. — Fig. 12. Nitzschia elongata: a, front view ; b, side 

 view. — Fig. 13. Navicula inequalis. — Fig. 14. Navicula 

 lanceolata. — Fig. 15. Surirella Jenneri : a, front view; 

 b, end view. — Fig. 16. Navicula. 



PLATE CIII. 



Figs. 1 and 2. Zygnema insigne. — Fig. 3. Coccochloris cysti- 

 fera. — Fig. 4. Coccochloris variabilis. — Fig. 5. Coccochloris 

 obscura. 



