The Diatoms of Nebraska 59 



straight or indented in the middle ; terminal nodules near the ven- 

 tral margin; striations distinct, 7-9 in 10 /x. Fig. 153 is the form 

 called var. elongata Grun. 



With other algae : Dismal River, St. Paul. 

 Fossil : Greeley County, Mullen. 

 Little White River, S. Dak. 



4. Eunotia lunaris (Ehr.) Grun. in V. H. Syn., p. 144, pi. 55, 



figs. 2-6. 1885. 



Syncdra lunaris Ehr. in Ahh. Bed. Akad., p. 8/. 18^1. 



PI. 5, figs. 156-162; pi. 22, fig. 818. 



Arcuate, 35-143 /x long, 4-8 /x wide; width uniform throughout 

 the entire length except at the ends, which are usually slightly 

 constricted on the dorsal margin, making the ends rostrate or capi- 

 tate ; terminal nodules round, distinct, on the ventral side ; stri- 

 ations granular, 12-15 ^^ ^o fx. Sometimes the cells have a single 

 or a double curve, making the form called var. bilunaris (figs. 

 160-162). 



Common in creeks, ponds, lakes, tanks, etc. : Anselmo, Atkinson, Auburn, 

 Bellevue, Big Alkali Lake, Broken Bow, Brownlee, Cedar Creek, Central 

 City, Clear Lake, Culbertson, Dewey Lake, Dismal River, Dunning, Emer- 

 ald, Fremont, Grand Island, Hackberry Lake, Halsey, Hyannis, Lin- 

 sohi, Lodi, Long Pine, New Helena, O'Neill, Osage, Pelican Lake, Peru, 

 St. Michael, Seneca, Talmage, Tekamah, Thedford, Valentine, Wann, 

 West Point, Whitman, Woodlake. 



Fossil : Agate, Cherry County, Merriman, Mullen, Spalding, Thed- 

 ford, Valentine, Williams's Canyon. 



Cheyenne, Wyo. ; Cutmeat, Rapid City, S. Dak. ; Sully's Hill, N. Dak. ; 



Fresno, Stockton, Cal. 



5. Eunotia diodon Ehr. Inf., p. ip2. 18^8. 

 PI. 5, fig. 163. 



Slightly arcuate, 34-50^11 long, 7-8 /x wide; ventral margin 

 slightly concave, dorsal margin convex with two inflations ; apices 

 sometimes capitate, not bent backward ; terminal nodules distinct, 

 near the ventral side; striations distinct, 8-10 in 10 /x. 



In ponds, rivers, lakes, etc.: Clear Lake, Dismal River, Hackberry 

 Lake, Halsey, Seneca. 



Fossil : Agate, Cherry County, Mullen, Valentine. 



