2 13 



22 "^23 



IV. — Diatoms, i, 2, 3, 4, Melosira. 5, vStephaiiodiscus. 6, 7, Eunotia. 

 8, Stepbanodiscus. 9, 10, Cvclotella. ii.Meridion. 12, 13, 14. nialouia. 15, 

 Fragilaria. 16, Stauroaeis. ' 17, Cocconeis. 18, Frustulia. 19, 20, Nitzcbia. 

 21, 22, Svnedra. 23, Gyrosigma. 24, 25, 26, 27, Navicula. 28, Tabellaria. 

 29, 30, Gonipbonema. 31, 32, Cainpvlodiscus. 33, Cymbella. 34, Pmnulana. 

 35, Epitbemia. 36, Tabellaria. 37, Asterionella. 38, Sunrella. 39, 40, 

 Achnantbidium. 41, Ampbora. 



