PLATE XLII. 



Figures magnlfled 500 diameters, excepting the Micrasterias only about 

 one-half as much. 



Page. 

 Fig. ]. MiCBASTEBiAS SwAiNEi, Hastings, . . . .119 



" 2. MiCRASTEEris KiTCHELii, WoUe, variety. Pond, Malaga, 



New Jersey, . . .129. 



Figs. 3-5. Xanthidium antelopaeum, Kg., . . . . 101 



Var. truncatum, Hastings, front, 



lateral and end views, . 101 



" 6, 7. Staurastkum megalonotum, Nord., . . . 141 



Var. obtueum, Hastings, . 141 



Nord.'s Spitz., Des. Arcto. and Des. Groen. 



" 8-11. Staukastkum CKESCENTCM, Hast., front and end views, . 153 



" 12, 13. EUASTBUM VEBBUCOSUM, Ehrb., .... Ill 



Var. simplex, Joshua, . .111 



" 14, 15. Staubastbum Saxonicdm, Bulnh., . . 154 



Var. pentagonum, WoUe, front 



and end views, . . . 154 



" 16, 17. EaASTBUM Hastinqsii, Wolle, . . . ." 113 



