PLATE XIII. 



Figures magnified .500 diameters. 



Fig-. 1. XAVICULA VIRIDIS, Kg., K. B., p. 97, 4, f. IS; 30, f. 12 ; Frit. p. 



907, 9, f. 133-136. 

 Figs. 2-4. NOBILIS, Ehrb., Mik., 11, f. 24a.b., Donk., B. D., p. 



:s, 11, f. i; vide Fig. 6, below. 

 Fig- 3. MAJOR, Kg., K. B., p. 97, 4, f. 19, 20; Frit., p. 896, 7, 



f. 65 ; 12, f. 15, 31 ; 16, f, 1-6 ; Schm. At., 42, f. 8-10, 



Sm. Sp. T., No. 294. 



GIGAS, Kg., Schm. At., 42, f. 1, 4; K. B., p. 98. 

 'i. NOBILIS, Ehrb. (K. B.), p. 98, 4. f. 24; Mik., 15, A., 



f. 13; 15 B. f. 7 ; Schm. At., 43, f. 13. 

 Figs. 7, 9. VIRIDIS, Kg., same as Fig. 1, above. One of our 



most common and widely distributed fresh water 



diatoms; very variable in size. 

 !l > I() - VIRIDIS, front views of frustules as often seen in 



pairs, or sometimes four or more united. 



