The Diatoms of Nebraska 93 



leaving a rectangular hyaline space about one-half the width of the 

 valve or sometimes extending across the entire width of the valve ; 

 terminal nodules expanded laterally. Cells often cohering in fila- 

 ments. 



In creeks, rivers, ponds, etc., especially with green algae, also fossil: 

 Alma, Andrews, Ashland, Benkleman, Broken Bow, Brownlee, Burge, Clear 

 Lake, Crawford, Culbertson, Dewey Lake, Dismal River, Dunning, Fairbury, 

 Fremont, Gordon Creek, Grand Island, Hackberry Lake, Halsey, Lakeside, 

 Long Pine, Louisville, Nebraska City, Norfolk, New Helena, North Platte, 

 Oakdale, Orella, Orleans, Pleasant Dale, Red Cloud, Ruby, Rupert, St. 

 Paul, St. Michael, Seneca, Seward, Snake River, Stanton, Stromsburg, 

 Talmage, Thedford, Trenton, Valentine, Wann, West Point. 



Fossil: Agate, Greeley County, Hay Springs, Loup City, Merriman, 

 Spalding. 



Little White River, S. Dak. ; Stockton, Cal. 



14. MiNUTISSIMAE 



A. Valves lanceolate. 67. A'', cocconciformis. 

 A A. Valves elliptical, very small. 



b. Striations very fine. 68. A^. atomoidcs. 



bb. Striations coarser. 69. N. mutica. 



6y. Navicula cocconeiformis Greg, in Quart. Jour. Mic. Soc, IV, 

 p. 6, pi. I, fig. 22. 1856. 



PI. 12, fig. 448. 



Elliptical or lanceolate, sometimes slightly swollen in the middle, 

 26-48/* long, 9-13 )u, wide; apices rounded or obtuse; striations 

 slightly radiate, granular, those opposite the central nodule of un- 

 equal length, about 18 in 10 fx. in the middle, 28-30 in 10 /u, at the 

 ends. 



In creek, Humboldt. 



68. Navicula atomoides Grun. in V. H. Syn., p. 107, pi. 14, fig. 11. 

 1885. 

 Namcula minima var. atomoidcs CI. Syn. Nav. Diaf., II, p. 



128. i8p4. 

 PI. 12, figs. 449-450- 



Elliptical or linear-elliptical, 8-12 /a long, 2.7-3 /x wide, ends 

 rounded; striations slightly radiate, 27-30 in 10 fx, shortened oppo- 

 site the central nodule, leaving a pseudostauros. Cells often united 

 in bands of 3 or 4. 



