Tlic Diatoms of Nebraska 97 



5. Stauroneis linearis Ehr. Amcr., p. i^^, pi. i, fig. II, 11. 



1843. 

 Stauroneis svuitJiii Grun. Wien. Verh., p. 464, pi. VI, fig. 16. 



i860. 

 PI. 12, fig. 469. 



Oblong or lanceolate, 20-30 /x long, 7-8 ^a wide, triundulate with 

 middle inflation larger ; stauros narrow, slightly wider at the ex- 

 tremities ; apices apiculate ; striations slightly radiate, about 30 in 

 lO/t; cells united in short bands. 



In creeks, rivers, etc.: Arago, Dewey Lake, Dunning, Grand Island. 

 Long Pine, Mason City, Tekamah, Thedford, Wahoo, Wann. 

 Fossil : Agate. Merriman. 

 Blackpipe, Rapid City, Rosebud, Turtle River, S. Dak. ; Fresno, Cal. 



6. Stauroneis legumen Ehr. Ahh., p. 755, pi. I, 2, fig. 5. 1844. 

 PI. 12, figs. 47(^471- 



Linear, triundulate, 21-35^ long, 4.5-8/* wide; apices rostrate- 

 capitate; striations radiate, 27-30 in io/a; stauros reaching nearly 

 to the margins, not dilated outward ; cells united in short bands. 



Gordon Creek, Red Cloud. 

 Fossil : Cherry Countj'. 



22. Diploneis 



Diploneis Ehr. 1840. 



Usually short, constricted in the middle or not, usually with 

 obtuse or rounded ends ; fresh-water species elliptical ; central 

 nodule more or less quadrate, prolonged into horns or processes 

 which lie parallel to the raphe. On both sides of the horns are 

 depressions or furrows of more or less breadth. General structure 

 like Naincnla, except that the central nodule is prolonged. 



Diploneis elliptica (Kiitz.) CI. Syn. Nav. Diat., I, p. g2. 18^4. 

 Navicida elliptica Kiitz. Bacill., p. p8, pi. 30, fig. 55. 1844. 



PI. 13, figs. 475-482. 



Oval-elliptic or oblong-elliptic, 12-55^ long, '/-22 jx wide; raphe 

 heavy, central nodule quadrangular with horns slightly curved ; 

 striations composed of puncta, 7-15 in 10 /x, nearly perpendicular 

 to the margin of the A-alve. The forms called var. ohlongclla and 

 var. ininima are found. 



