The Diatoms of Nebraska 57 



9. Synedra tabulata (Ag.) Kiitz. Bacill., p. 68, pi. 15, fig. 10. 

 1844. 



Diatoma tahulatmn Ag. Consp. Dial., p. 50. 18^0. 



Synedra affinis var. tabulata V. H. Syn., p. 75?. 188^. 



PI. 4, figs. 144-146. 



Lanceolate with ends sometimes slightly rostrate-capitate, 90- 

 175 /x long; striations short, leaving a very wide pseudoraphe, 

 10-13 in 10 /a; frustules arranged radially. 



Common in brackish water; Arbor, in salt marsh ; Lincohi, in SaU Creek; 

 Scottsbluff, Thedford. 



Devils Lake and fresh water near Devils Lake, N. Dak. 



15. Asterionella 



Asterionella Hassall in Micr. Exam., p. 10. 1856. 



Etym., diminutive of Greek aarrip, star, referring to the radial 

 arrangement of the cells. 



Cells elongated, linear ; apices unequally capitate ;" girdle face 

 linear with apices unequally inflated ; cells radially arranged. 



Asterionella gracillima (Hantzsch) Heiberg. Consp., p. 68, pi. 6, 

 fig. 19. 1863. 



Diatoma gracillimmn Hantzsch in RabcnJi. Alg., No. 1104. 



PI. 2, figs. 88-90. 



Valves very narrow, linear, tapering toward the rounded capi- 

 tate ends, the basal end larger than the other, 42-100 /i, long, about 

 2 /jL wide in the middle; striations 15-17 in lO/x, interrupted by a 

 very narrow rachis. 



In San Joaquin River, Stockton, Cal. 



16. Eunotia 



Eunotia Ehr. in Bcr. Bcrl. Akad., p. 45. 183^. 



Etym., Gr. ev , well, and j'wtos, back, in reference to the 

 .strongly curved dorsal margin. 



Cells free, or united in filaments; or attached ; in girdle view 

 rectangular-oblong, in valve view arcuate, the convex margin often 

 undulate ; valves with transverse striations, no ribs, pseudoraphe 

 not evident ; polar noditles present, central nodule wanting ; 



