74 



Clarence J. Elmore 



22. Navicula menisculus Schiim. Preuss. Dial., 11, p. 56, pi. 2, 



fig. 33. 1864. 



PI. 8, figs. 290-293. 



Elliptical-lanceolate, 15-32/x, long, 5.5-13 /* wide, attenuate or 

 attenuate-rostrate; striations radiate, becoming parallel or con- 

 verging at the ends, 8-15 in lOju, closer at the ends than in the 

 middle, the ones in the middle sometimes not much shortened. 



In creeks and rivers : Grand Island, Long Pine, Ruby, Seneca. 



23. Navicula salinarum Grun. Arct. Diat., p. 33, pi. 2, fig. 34. 



1880. 



PI. 8, figs. 294-295. 



Broadly lanceolate with capitate apices, 24-35^11 long, 7-15 ju, 

 wide ; striations radiate in the middle and converging at the ends, 

 14-16 in 10 /A, shortened opposite the central nodule, leaving a 

 circular hyaline space. 



In pond. Ruby. 



Little White River, S. Dak. 



24. Navicula cincta (Ehr.) Ralfs in Pritcli. Inf., p. poi. 1861. 

 Pinnularia cincta Ehr. Mikr., pi. 10.2, fig. 6. 1843. 



PI. 8, figs. 296-298. 



Elliptical-lanceolate, 20-40 /x long, 5-7 /x wide, from narrowly to 

 broadly rounded at the apices ; striations usually indistinct, about 

 12 in 10 )U,, the middle ones more distant, radiate except at the ends, 

 where they are converging, slightly shortened around the central 

 nodule, leaving a small transverse hyaline space. 



Var. heuflerii Grun. and var. icptoccphala Breb. appear to be 

 mere forms. 



In fresh and brackish water : Arbor, Fairbury, Grand Island, Long Pine, 

 Louisville, Nebraska City, Nemaha City, Orella, Pawnee City, Peru. Salem, 

 7'almage, Weeping Water. 



Devils Lake, N. Dak. 



25. Navicula gracilis Kiitz. BacilL, p. pr, pi. 3, fig. 48; pi. 30, 



fig. 3/. 1844. 

 PI. 8, figs. 299-303. 



Narrowly lanceolate, 38-80 /a long. 8-10 /x, wide, apices acute; 

 striations 10-12 in 10 /a, radiate in the center, then straight, and 



