124 Clarence J. Elmore 



In creeks, rivers, lakes, etc., also fossil : Andrews, Burge, Crawford, 

 Grand Island, Hackberry Lake, Haigler, Long Pine, New Helena, Nor- 

 folk, North Platte, Seneca. Thedford, Valentine. 



Fossil : Agate, Mullen, Valentine. 



Belvidere, Rosebud, Weta, S. Dak. ; Cheyenne, Wyo. ; Blackhand, Gran- 

 ville, Rio Grande, Ohio. 



32. Amphora 



Amphora Ehr. in Bcr. Berl. Akad., p. 205. 1840. 



Okcdcnia Etielenstein. 



Etym., amphora, a Roman water jar, from a fancied resemblance 

 to this vesseL 



Cells single, mostly free, elliptical or rectangtilar in girdle view, 

 sometimes with cimeate interzones ; valves lunate, not symmetrical ; 

 raphe excentric, near the concave margin, doubly arcuate ; central 

 nodule round or transversely elongated ; surface transversely punc- 

 tate-striate. Chromatophore a single plate lying next to the con- 

 cave side of the valves and folding back, lining both valves. 

 Auxospores two from two mother cells. 



A. Freshwater species. ' i. A. ovalis. 



AA. Salt water species. 



b. Small forms. 2. A. salina. ■ 



bb. Large forms. 3. A. proteus. 



I. Amphora ovalis Kiitz. Bacill., p. loj, pi. 5, jigs. 55, 59. 1844. 



Fntsfitlia ovalis Kiitz. Syn. Diat., p. it, fig. 5. 18^4. 



PI. 17, figs. 630-643. 



Cells oval, 20-84 /* long, 10-16^ wide, inflated in the middle, 

 apices truncate ; valves lunate with acute ends ; raphe close to the 

 ventral margin; striations punctate, 8-16 in 10^. Very variable 

 and presenting several forms or varieties. 



Very common, usually epiphytic on other algae, also fossil : Alma, An- 

 drews, Anselmo, Ashland, Auburn, Bellevue, Benkleman, Big Alkali Lake, 

 Battle Creek, Broken Bow, Brownlee, Burge, Central City, Chadron, Clear 

 Lake, Cody Lake, Crawford, Culbertson, Dewey Lake, Dunning, Emmett, 

 Fairbury, Fremont, Gordon Creek, Grand Island, Halsey, Hackberry Lake, 

 Haigler, Holt County, Humboldt, Hyannis, Lakeside, Lincoln, Little Alkali 

 Lake, Lodi, Long Pine, Milford, New Helena, North Platte, Northport, 

 Oakdale, Omaha, O'Neill, Orella, Orleans, Phalaris Lake, Pleasant Dale, 

 Plattsmouth, Red Cloud, Ruby, Rupert, St. Michael, St. Paul, Salem, 



