The Diatoms of Nebraska 99 



Bow, Brownlee, Cairo, Callaway, Central City, Cody Lake, Columbus, 

 Crawford, Dismal River, Dunning, Emerald, Grand Island, Hackberry 

 Lake, Halsey, Lodi, Louisville, Orella, Pelican Lake, Pleasant Dale, Roca, 

 Ruby, St. Paul, Scottsbluff, Seneca, Stanton, Tekamah, Thedford, Trenton, 

 Valentine. 



Fossil : Agate, Cherry County, Mullen, Valentine. 



Norris, Rapid City, Rosebud, S. Dak. ; Stockton, Cal. 



2. Achnanthes microcephala (Kiitz.) Grun. in CI. & Gnin. Arct. 



Diat., p. 22. 1880. 



AchnantJiidium microcephalum Kiitz. Bacill., p. 75, pi. 5, figs. 

 13, ip. 1844. 



PL 13, figs. 488-489. 



Narrowly lanceolate, 9-26 /x long, 3-4^1. wide; apices capitate; 

 upper valve with parallel striations. all extending to the pseudo- 

 raphe except the middle ones, 30-36 in 10 /x; striations of the 

 lower valve slightly radiate, those in the middle much shortened, 

 leaving a transverse hyaline space ; cells geniculate, often united in 

 bands. 



In creeks, rivers, tanks, etc., also fossil : Andrews, Burge, Grand Island, 

 Hemingford, Long Pine, Scottsbluff, Woodlake. 



Fossil : Agate. 



Cheyenne, Wyo. ; Blackpipe, S. Dak. ; Devils Lake, N. Dak. ; Fresno, 

 Stockton, Cal. ; Emporia, Kansas. 



3. Achnanthes biasolettiana (Kiitz.) Grun. Arct. Diat., p. 22. 



1880. 



Synedra biasolettiana Kiitz. Bacill., p. 63, pi. 3, fig. 22. 1844. 



PI. 13, figs. 490-491- 



Broadly lanceolate, more or less swollen in the middle, 10-20 fx. 

 long, 4-6 /A wide; apices broad, rounded, sometimes slightly capi- 

 tate; striations slightly radiate, 20-25 in \o fx. Cleve, Syn. Nav. 

 Diat., II, p. i8p, gives the length 55-31 /x, in which he is followed 

 by Schonfeldt. Diat. Dentsch., Oest., und Sclnv., p. jj. It is 

 likely that Cleve's measurement was intended to be 5.5-31 ix. Van 

 Heurck, Diat., p. 281, gives the length about 10 /x, which agrees 

 with both his and Schonfeldt's figures and with the specimens 

 found in Nebraska. 



Fossil : Agate. 



