The Diatoms of Nebraska 75 



converging at the ends, those opposite the central nodule equally 

 shortened. 



In creeks and rivers : Crawford, Grand Island, Hackberry Lake, Oak- 

 dale, Seneca. 



26. Navicula vulpina Kiitz. Bacill., p. 92, pi. ^, fig. 4^. 1844. 

 PI. 22, fig. 825. 



Lanceolate, ends obtuse or slightly attenuate, 75-140 //, long, 14- 

 i6fjb wide; striations radiate in the center, converging at the ends, 

 shortened opposite the central nodule, leaving a rectangular space, 

 lo-ii in lO/A. 



Fossil in Pliocene stratum : Valentine. 

 New Concord, Ohio. 



27. Navicula viridula Kiitz. Bacill., p. pi, pi. ^o, fig. 47; pi. 4, 



figs. 10, 75. 1844. 



PI. 8, fig. 304.' 



Broadly lanceolate, 33-70 /* long, 7-10 /x wide, apices tapering, 

 rostrate; striations 8-14 in 10 /x, radiate in the middle, converging 

 at the ends, shortened around the central nodule, leaving a round 

 hyaline space. 



In watering trough, Cheyenne, Wyo. 



28. Navicula radiosa Kiitz. Bacill., p. pi, pi. 4, fig. 2^. 1844. 

 PI. 8, figs. 305-311- 



Lanceolate, 30-70 /x long, 7-12 /* wide, margin from center to 

 ends convex, straight, or concave, but attenuate at the ends; stri- 

 ations radiate in the middle, slightly curved, converging at the 

 ends, extending nearly to the raphe, but slightly shortened opposite 

 the central nodule, 9-12 in 10 ix. Includes N. radiosa var. acuta 

 (W. Sm.) Grun. 



In creeks and rivers, also fossil: Andrews, Anselmo, Bellevue, Benkle- 

 man, Crawford, Culbertson, Dismal River, Gordon Creek, Grand Island, 

 Hackberry Lake, Halsey, Lincoln, Long Pine, Meadow, New Helena, 

 North Platte, Oakdale, Orleans, Red Cloud, St. Michael, St. Paul, Snake 

 River, South Bend, Thedford, Trenton, Valentine, Whitman, Woodlake, 

 Woodlawn. 



Fossil : Agate, Greeley County, Loup City, Merriman, Mullen, Valentine, 

 Williams's Canyon. 



