TJie Diatoms of Nebraska 29 



McMillan, and that from Merriman by Mr. L. E. Fagan. The 

 collection from Loup City was furnished by Mr. Clarence O. Peter- 

 son, and that from Hay Springs by Prof. R. W. Ellis. 



Much of the recent material has been collected by friends of the 

 writer, among whom are: Prof. W. E. Allen, Fresno and Stock- 

 ton, Calif. ; Rev. J. M. Bates. Atkinson, Ewing, Long Pine, and 

 Red Cloud; Prof. A. T. Bell, Crete;. Prof. C. E. Bessey, Ashland; 

 Miss Grace Bradburn (Mrs. Chas. Frisch), Broken Bow; Miss 

 Pearl Chase, Ainsworth ; Prof. F., E. Clements, Holt County ; Miss 

 Alba Cosner, New Helena ; Miss Harriet Ege, Rosebud, S. Dak. ; 

 Miss Cora Elmore (Mrs. C. H. Bancroft), Talmage; Mr. Wm. 

 Fleming, Cheyenne, Wyo. ; Prof. J. H. Flodman, Wahoo ; Miss 

 Ethel Hansen, Grand Island ; Mr. W. J. Hesser, Plattsmouth ; 

 Miss Isabel Johnston, Lodi ; Mr. Ray Kellenbarger, Anselmo; Mr. 

 E. F. Lange, Fairbury ; Mr. Ray McCann, Estes Park, Colorado ; 

 Mr. Theodore Moline, Polk; Prof. A. K. Peiterson, Weeping 

 Water; Prof. N. F. Petersen, many places in eastern Nebraska; 

 Prof. Roscoe Pound, Sheridan County, Cherry County; Prof. J. 

 H. Powers, Colorado; Prof. A. A. Reed, Crete; Mr. J. A. Reed, 

 Blue Springs; Mrs. Perry Robbins, New Helena; Mr. Windom 

 Rosene, Stromsburg; Prof. DeAlton Saunders, Bellevue; Miss 

 Laura Sutherland, Chippewa Falls, Wis. ; Miss Lilian Sutherland, 

 Pawnee City; Miss Fae Troyer (Mrs. Wm. Fleming), Turtle 

 River and Dallas, S. Dak. ; Prof. J. E. Weaver, Crete ; A. C. 

 Whitf ord. Dismal River and many other places in the Sand Hills ; 

 Prof. Elda R. Walker, lakes in Sand Hills ; Prof. R. T. Young, 

 Devils Lake, N. Dak. Besides these much material from the 

 vicinity of Grand Island has been furnished by members of the 

 writer's own family. 



Artificial Key to the Genera 

 A. Valves round. 



b. Cells without horns (Fam. Coscinodiscaccae). 



c. Cells united in filaments. r. Lysigoniuni, page 2>'^. 



cc. Cells single. 



d. With distinct central and marginal portions. 



2. CyclotcUa, page 39. 

 dd. Central and marginal portions grading into one another. 

 c. With marginal spines. 3. Stephanodiscus, page 40. 



