ConU. Nal. Herb., Vol. X. 



Plate LII 



1 



2 



o 





■J 



*0 1»*^«^-O^.' 









e^ o v* '*-"'■ * ft* 



6 Q C O • ftC 



4 



5 



3 



6 



7 



Diatoms of the Genera Plagiogramma and Navicula 



