The Diatoms of Nebraska 119 



Elliptic, 30-52/* long, ii-i4ju. wide, dorsal margin more convex 

 than the ventral ; ends obtuse, sometimes slightly attenuate ; raphe 

 straight or only slightly curved toward the dorsal margin ; stri- 

 ations finely granular, 10-14 in 10 /x in the middle on the dorsal 

 side, closer elsewhere, nearly perpendicular to the margins, extend- 

 ing nearly to the raphe, but leaving a distinct space which is 

 slightly wider opposite the central nodule. 



In creeks at Andrews and in Clear Lake. 



9. Cymbella gastroides Kiitz. BacilL, p. /p, pi. 6, fig. 4b. 1844. 

 Fntstulia gastroides Kiitz. Diat., p. if,, fig. p. 18^4. 

 Cocconema aspermn Ehr. Ber. Berl. Akad., p. 12, J , fig. i. 



1840. 



Cynibclla aspera (Ehr.) CI. Syn. Nav. Dial., I, p. ly^. 18^4. 



PI. 16, figs. 601-606. 



Broadly lunate, 54-180 /x long, one specimen 244 /a long, 19-37 /x. 

 wide, ventral margin slightly concave, usually gibbous ; ends ob- 

 tuse; raphe arcuate with ends bent toward the dorsal margin; 

 striations perpendicular to the margins, 5-9 in 10 /x on the dorsal 

 side in the middle, closer elsewhere, composed of coarse dots, 

 slightly shortened, leaving a distinct space along the raphe which 

 is wider opposite the central nodule. Varies from nearly semi- 

 circular to long lunate. Dififers from C. lanceolata in its usually 

 broader form, striations of coarser dots, and wider space along the 

 raphe. Fig. 606 is of a fossil form found at Thedford. 



Common in creeks, rivers, springs, tanks, etc., with Cladophora, Spiro- 

 gyra, or other filamentous algae, also fossil : Andrews, Anselmo, Bellevue, 

 Benkleman, Burge, Callaway, Central City, Crawford, Culbertson, Dismal 

 River, Dunning, Gordon Creek, Grand Island, Hackberry Lake, Haigler, 

 Halsey, Holt County, Lodi, Long Pine, Louisville, Meadow, New Helena, 

 Newport, North Platte, Northport, Oakdale, Orelans, Red Cloud, Ruby, St. 

 Paul, Seneca. Snake River, South Bend, Tekamah, Thedford, Trenton, 

 Valentine. Wann. 



Fossil: Agate, Cherry County. Greeley County, Hay Springs, Mullen, 

 Spalding, Thedford, Valentine, Williams's Canyon. 



Blackpipe, Cutmeat, Little White River, Norris, Rapid City, Rosebud, 

 S. Dak. ; Cheyenne, Wyo. ; Ft. Collins, Colo. ; Stockton, Cal. 



10. Cymbella lanceolata (Ehr.) Kirchn. Alg. ScJdes., p. 188. 



1878. 

 Cocconema lanceolatum Ehr. Inf., p. 224, pi. iq, fig. 6. 18^8. 



