The Diatoms of Nebraska 73 



c. Striations finely punctate. 39. A'', dicephala. 



cc. Striations coarsely punctate. 40. A'', amphibola. 



20. Navicula oblonga Kiitz. BacUl., p. 97, pi. 4, fig. 21. 1844. 

 FrustuJia oblonga Kiitz. Alg. Dec, A^o. 84. 18^4. 

 Navicula macilenfa Ehr. Inf., p. 18^. pi. 21, fig. zj. 18^8. 

 PI. 8, figs. 280-282; pi. 22, fig. 843. 



Oblong-linear, 92-160^ long, 14-17 /i. wide; margins from cen- 

 ter to apices convex or straight, very slightly constricted below the 

 broadly rounded apices; raphe distinct but delicate; striations 6-8 

 in 10 (U., all radiating at an angle of 45°, except a few at the ends, 

 which are converging, flexuous. those near the ends abruptly 

 broken, shortened opposite the central and terminal nodules, leav- 

 ing circular areas. 



Common among higher algae and also as fossil : Andrews, Anselmo, 

 Benkleman, Big Alkali Lake, Cherry County, Dewey Lake, Dismal River, 

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

 Lakeside, Long Pine, New Helena, North Platte, Pelican Lake, Rupert, 

 St. Paul, Scottsbluff, Seneca, Thedford, Valentine, Wahoo, Wann, Whit- 

 man, Willow Lake. 



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

 Merriman, Mullen, Spalding, Thedford, Valentine, Wheeler County. 



Cutmeat, Rosebud, Turtle River, S. Dak. ; Court Lake, Devils Lake. 

 Su'.ly's Hill, N. Dak.; Cheyenne, Wyo. 



21. Navicula peregrina (Ehr.) Kiitz. BacilL, p. gy. pi. 28, fig. 



52. 1844. 

 Pinnularia peregrina Ehr. Anier., p. /jj, pi. I, figs. fj-6. 



PI. 8. figs. 283-289. 



Elliptical to broadly lanceolate or rhomboidal, sometimes at- 

 tenuate-rostrate, 34-80^ long, 8-18 /A wide; striations very dis- 

 tinct, 6-12 in 10 fx, radiate in the center and converging at the ends, 

 extending almost to the raphe, about 3-5 of the middle ones short- 

 ened, the alternate ones shorter, leaving a transverse hyaline space. 



With higher algae in creeks and ponds: Callaway, Grand Island, Lin- 

 coln, Long Pine, North Platte, Red Cloud, Weeping Water. 

 Rosebud, S. Dak. 



