The Diatoms of Nebraska 47 



10 yu,. The specimens found agree more nearly with D. inflata 

 W. Sm., which is probably only a form of D. tenuis. 



In creek, western Colorado. 



Family 5. MERIDIONACEAE 



Rachis a narrow unmarked strip, no raphe; cells usually much 

 shorter than broad, usually in filaments, cuneate in girdle view. 



10. Sceptroneis {Opephora, Peronia) 



Sceptroneis Ehr. in Ber. Bed. Akad., p. 264. 1844. 



Etym. from Gr. a-Kyj-n-Tpov , scepter, on account of the rod-like 

 form of the valve. 



Cells both in valve and girdle view cuneate, united; without 

 septate girdle or transverse septa ; pseudoraphe present, often very 

 broad ; terminal nodules sometimes present ; valves with trans- 

 verse beaded striations, beads often united into slit-like or button- 

 hole-like striations. 



/2. With heavy ribs. i. S. pacifica. 



AA. With delicate striations. 2. S. fibula. 



1. Sceptroneis pacifica (Grun.) Elmore. 



Fragilaria pacifica Grun. in Wicn. Verh., p. j/j, pi, 5, fig. ip. 



1862. 

 Opephora pacifica (Grun.) Petit. Diat. Cape Horn, p. 1^0. 



1888. 

 PI. 2, figs. 47-50- 



Cells ovate, 20-30 ju, long, with very heavy linear-ovate ribs, 5-10 

 in 10 fx] pseudoraphe narrow. 



In ponds, rivers, etc., also fossil : Andrews, Benkleman, Brownlee, Burge, 

 Crawford, Culbertson, Dismal River, Dunning, Fremont, Gordon Creek, 

 Grand Island, Haigler, Halsey, Ithaca, Long Pine, Melia, Norfolk, North 

 Platte, Oakdale, Red Cloud, St. Michael, St. Paul, Seneca, Snake River, 

 Stanton, Valentine, Wann, West Point, Whitman. 



Fossil : Greeley County, Mullen, Spalding, Thedford, Valentine. 



Blackpipe, Little White River, Rosebud, S. Dak.; Cheyenne, Wyo.; Rod- 

 ney, Ohio. 



2. Sceptroneis fibula (Breb.) Schiitt in Eng. & Prant. Natur. 



Pfianz., I, lb, p. lOp. ipoo. 



