The Diatojus of Nebraska m 



a rounded hyaline space with an isolated dot. The form called 

 var. insignis is the only one yet found in Nebraska. 



With Vauchcria, Crete. 



7. Gomphonema montanum Schum. Diat. Tatra, p. 6"/, pi. ^, fig. 



35h. 1867. 



GompJionema siihclavatum Grun. Diat. Fr. Jos. Land, p. 46, 

 pi. I, fig. 13. 1884. 



PL 14, figs. 54(^553- 



Clavate, 10-90 ;u, long, 5-13 /^ wide, sometimes more or less 

 triundulate, apices rounded; striations 7-14 in 10 fx, slightly radi- 

 ate, 2 or 3 of those on one or both sides of the central nodule 

 shortened, leaving a hyaline space in which is an isolated dot. 

 Very variable in form and size. The varieties subclavatiiin and 

 commutatum are probably only forms. 



Very common in water everywhere, also fossil : Alma, Andrews, Ansel- 

 mo, Ashland, Atkinson, Benkleman, Bratton, Brock, Broken Bow, Brown- 

 lee, Burge, Callaway, Cellar Creek, Central City, Chadron, Clear Lake, 

 Cody Lake; Columbus, Crawford, Crete, Culbertson, Dewey Lake, Dismal 

 River, Dunning, Emerald, Emmett, Fremont, Grand Island, Hackberry 

 Lake, Halsey, Hemingford, Holbrook, Hyannis, Lakeside, Lincoln, Lodi, 

 Long Lake, Long Pine, Louisville, Mason City, Meadow, Melia, Milford, 

 New Helena, Newport, Norfolk, North Platte, Northport, O'Neill, Orella, 

 Orleans, Pehcan Lake, Phalaris Lake, Pleasant Lake, Red Cloud, Ruby, 

 Rupert, St. Michael, St. Paul, Scottsbluff, Seneca, Seward, South Bend, 

 Stanton, Stromsburg, Talmage, Tekamah, Thedford, Tioga, Trenton. Val- 

 entine, Wahoo, Wann, Watts Lake, Weeping Water, West Point, Whit- 

 man, Willow Lake, Woodlake. 



Fossil : Agate, Cherry County, Greeley County, Hay Springs, Loup City, 

 Merriman, Mullen, Spalding, Thedford, Valentine, Williams's Canyon. 



Belvidere, Blackpipe, Conata, Corn Creek, Cutmeat, Kadoka, Little 

 White River, Norris, Redleaf, Rosebud, S. Dak. ; Cheyenne, Wyo. ; Devils 

 Lake and fresh water near Devils Lake, N. Dak. ; Chippewa Falls, Wis. ; 

 Fresno, Cal. ; Granville, Ohio; Emporia, Kansas. 



8. Gomphonema validum CI. Syn. Nav. Diat., I, p. 185. i8p^. 

 PI. 15, figs. 554-556. 



Clavate, regular, or slightly biconstricted ; apices rostrate-apicu- 

 late, cuneate, or rounded; 65-95 |U, long, 7-13 /u. wide; striations 

 slightly radiating, 5-7 in 10 jjl, shortened, leaving a moderately 

 wide longitudinal hyaline area not dilated in the middle ; isolated 

 dot often indistinct. 



