The Diatoms of Nebraska 79 



36. Navicula gastrum Ehr. Amer., p. jj?, pi. ^, VII, fig. 27,. 

 1843. 



PI- 9- figs. 337-338- 344. 



Elliptical with apices varying from broadly rounded to capitate, 

 25-45 /A long, II-I7/A wide; striations all radiate, 8-1 1 in 10 |u, 

 those around the central nodule alternately long and short, leaving 

 a round or transversely elongated hyaline space. 



In creeks, ponds, and rivers, usually with higher algae, also fossil : 

 Benkleman, Big Alkali Lake, Brownlee, Burge, Central City, Cody Lake, 

 Crawford, Dismal River, Dunning, Gordon Creek, Grand Island, Haigler, 

 Hyannis, Long Pine, Norfolk, North Platte. Phalaris Lake, Red Cloud, 

 St. Paul, Seneca, Stanton, Trenton, Valentine, Wann. Watts Lake, West 

 Point. 



Fossil : Agate, Loup City, Merriman. 



Cheyenne, Wyo. ; Little White River, Rapid City, S Dak. ; Devils Lake 

 and fresh water near Devils Lake, N. Dak. ; Blackhand, Ohio. 



2,"/. Navicula anglica Ralfs in Pritch. Inf., p. poo. 186 1. 



PI. 9, figs. 33^343- 



Elliptical with capitate ends, 23-40 /a long, 8-14 /i, wide; stri- 

 ations all radiate, 9-15 in 10 jx, shorter around the central nodule, 

 but not alternately longer and shorter. Fig. 342 is a small speci- 

 men, 14 /x, long, with 20 striations in 10 /x,. 



Common with other algae in creeks, rivers, ditches, ponds, etc. : Andrews, 

 Anselmo, Ashland, Benkleman, Burge, Cedar Creek, Central City, Cherry 

 County, Clear Lake, Crawford, Dismal River, Gordon Creek, Grand Island, 

 Hackberry Lake, Halsey, Ithaca, Long Pine, Louisville, New Helena, 

 Oakdale, Omaha, Pelican Lake, Red Cloud, St. Paul, Seneca, Snake River, 

 South Bend, Thedford, Valentine, Wann. Willow Lake. 



Blackpipe, Little White River, Rosebud, Turtle River, S. Dak.; Devils 

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

 Blackhand, Muskingum River, New Concord, Put-in Bay, Rodney, Ohio. 



38. Navicula placentula (Ehr.) Kiitz. BacilL, p. p^, pi. 28, fig. 

 57- 1844. 

 Pinmilaria placentula Ehr. Amer., p. 7?j, pi. ?, VII, fig. 22. 

 1843. 



PI- 9. fig- 345- 



Elliptical with apices varying from broadly rounded to capitate, 

 23-60 /A long, 8-28 /A wide; striations all radiate, 6-10 in 10 /x., 



