The Diatoms of Nebraska 117 



dorsal, 40-95 /x long, 14-24 /a wide, rostrate or rostrate-capitate; 

 raphe nearly straight; striations radiate, 6-10 in 10 ^a on the dorsal 

 side in the middle, elsewhere closer, extending nearly to the raphe 

 except opposite the central nodule, where they are shortened, leav- 

 ing a rounded hyaline space. 



Fig. 588 seems to be an abnormal form of C. cuspidata. 



In creeks, rivers, lakes, etc., also fossil: Bellevue, Dewey Lake. Dismal 

 River, Grand Island, Hackberry Lake, Halsey, New Helena, Pelican Lake, 

 Seneca, Snake River, Wahoo. 



Fossil : Agate, Cherry County, Greeley County, Loup City, Mullen, Spald- 

 ing, Thedford, Valentine, Wheeler County. 



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



3. Cymbella amphicephala Naeg. in Kiit::. Spec, p. 8qo. 1849. 

 PI. 16, fig. 589. 



Elliptic, 25-40 /A long, 9-10 fi wide, ventral margin convex or 

 nearly straight, ends rostrate or rostrate-capitate ; raphe nearly 

 straight, nearer the ventral margin ; striations radiate, 10-14 in 

 10 }x on the dorsal side in the middle, closer elsewhere, finely gran- 

 ular, extending nearly to the raphe, leaving a very narrow space 

 which is slightly wider opposite the central nodule. 



In creeks and lakes : Andrews, Clear Lake, Long Pine, Snake River. 

 In creek at Cheyenne, Wyo.; Rapid City, S. Dak.; Biackhand, New Con- 

 cord, Put-in Bay, Rodney, Ohio. 



4. Cymbella pusilla Grun. in A. Schm. Atlas, pi. p, figs. 36, 37. 



1875. 



PI. 16, fig. 590. 



Lanceolate, 23-40 /a long, 5-9 /a wide, apices acute, often slightly 

 rostrate; raphe straight; striations radiate, 11-18 in 10 /x in the 

 middle on the dorsal side, closer elsewhere, extending nearly to 

 the raphe throughout. 



In Pelican Lake. 



Devils Lake, N. Dak. ; Stockton, Cal. 



5. Cymbella leptoceras (Ehr.) Ral)enh. Siisszv. Diaf., pi. j, fig. 



14. i8ji3. Fl. En. Alg., p. 81. 1864. 

 Cocconema leptoceras Ehr. Amer., pi. i, II, fig. 50. 1843. 

 PI. 16, figs. 591-592. 

 Dorsal margin evenly curved, ventral nearly straight or slightly 



