100 Clarence J. Elmore 



4. Achnanthes linearis (W. Sm.) Grim. Arct. Dial., p. 23. 



1880. 

 Achnanthidiuni linearc W. Sm. Brit. Diat., II, p. 51, pi. 61, 



fig. 381. 1856. 

 PI. 13, figs. 492-493- 



Linear with rounded ends, 10-20 jx long, 3-4 /x, wide; upper valve 

 with narrow, linear axial area and parallel striations ; lower valve 

 without axial area and with small transverse central area ; stri- 

 ations radiate, 22-28 in 10 ju,; cells geniculate. 

 In Seven Springs at Long Pine. 



5. Achnanthes lanceolata (Breb.) Grun. Arct. Diat., p. 23. 



1880. 



AcJinanthidntm lanceolatum Breb. in Kiits. Spec. Alg., p. 5^. 

 1849. 



PI. 13, figs. 494-499- 



Narrowly elliptic-lanceolate to broadly elliptical, 1 1-35 yu, long, 

 4-8 jx wide ; upper valve with linear central axial area broadened 

 on one side in the middle into a broad horseshoe-shaped hyaline 

 area; striations granular, nearly parallel, 12-16 in 10 /x; lower valve 

 with narrow axial area and broad rectangular central area ; stri- 

 ations granular, slightly radiate ; cells geniculate. 



In creeks, tanks, ponds, lakes, etc. : Andrews, Ashland, Bnrge, Clear 

 Lake, Dismal River, Dunning, Gordon Creek, Grand Island, Halsey, Long 

 Pine, Louisville, Mason City, Milford, O'Neill, Orella, Orleans, Pleasant 

 Dale, Polk, Red Cloud, Snake River, Tekamah, Thedford, Valentine, 

 Wann, Watts Lake. 



Stockton, Cal. ; Court Lake, Sully's Hill, N. Dak. ; Blackhand, Granville, 

 Ohio. 



24. Cocconeis 

 Cocconeis Ehr. Inf., p. ipj. 1835. cm. Grun. Alg. Nov., p. 11. 

 186S. 

 Actinoncis Cleve; Hcteroncis Cleve. 



Etym., from Gr. K6KKo<i, berry, or grain, on account of its re- 

 semblance to a grain of wheat. 



Cells single, straight or curved in girdle view and the plane of 

 the upper valve with its margins turned downward ; valves round- 

 elliptical to circular, dissimilar, the lower concave with a true raphe 



