The Diatoms of Nebraska 109 



AA. No isolated dot. 



b. Hyaline area distinct. 13. G. oiivaceum. 



bb. Hyaline area narrow. . 14. G. exiguum. 



1. Gomphonema constrictum Ehr. Abh. Ber. Acad., p. (5?. 18^0. 



(According to Kiitz., Bacill., p. 86.) 



PI. 14, figs. 526-529. 



Cuneate, 37-60 /* long, /-ii/a wide, inflated in the middle and 

 deeply constricted between the middle and the upper end, which 

 is broadly roimded; striations granular. 10-12 in 10 /x, radiate, 

 alternately long and short around the central ngdule ; an isolated 

 dot on one side of the central nodule. 



In creeks, rivers, etc., also fossil : Andrews, Atkinson, Broken Bow, 

 Burge, Cedar Creek, Central City, Clear Lake, Cody Lake, Crawford, 

 Dewey Lake, Dismal River, Druly Lake, Dunning. Ewing, Fremont, Grand 

 Island, Halsey, Johnson, Lodi, Long Pine, New Helena, Newport, North 

 Platte, Oakdale, Pelican Lake, Rupert, Scottsbluff, Talmage, Tekamah, 

 Thedford, St. Michael, St. Paul, Seneca, Seward, South Bend, Stanton, 

 Thedford, Valentine, Wann, Weeping Water. Willow Lake. Woodlake. 



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

 Merriman, Mullen, Spalding, Thedford, Valentine, Wheeler County. 



Cutmeat. Rapid City, Rosebud, S. Dak. ; Cheyenne, Wyo. ; Stockton, Cal. ; 

 Ft. Collins, Colo. ; Blackhand, Ohio. 



2. Gomphonema acuminatum Ehr. Inf.. p. 21/, No. ^08, pi. 18, 



fig. 4. 1838. 



PL 14, figs. 530-534; pl- 23, figs. 845, 847. 



Cuneate, 19-70 /a long, 6-12 /x, wide, inflated in the middle, con- 

 stricted below the upper end, which is more or less triangular, 

 apiculate ; striations g-12 in 10 /x, radiate, grantilar, shortened on 

 one side of the central nodule, leaving a hyaline space in which is 

 an isolated dot. G. turris Ehr. is made a variety of G. acimii- 

 natuin by Cleve, Syn. Nov. Diat., I, 184. 



In springs, creeks, lakes, rivers, etc., with Spirogyra and other algae, 

 also fossil : Atkinson, Bellevue, Broken Bow, Central City, Clear Lake, 

 Cody Lake, Dismal River, Dunning, Fremont, Grand Island, Hackberry 

 Lake, Halsey, Hyannis, Lakeside, Long Pine, New Helena, North Platte, 

 Ruby, Scottsbluff, Snake River, Talmage. Tekamah, Thedford, Valentine, 

 Whitman, Woodlake. 



Fossil: Agate, Greeley County, Mullen, Thedford, Valentine. 



Blackpipe, Cutmeat, Little White River, Rapid City, Turtle River, S. 

 Dak. ; Chippewa Falls, Wis. 



