54 Clarence J. Elmore 



1. Synedra pulchella Kiitz. BacilL, p. 68, pi. 2g, fig. 8/. 1844. 

 PI. 3, figs. 91-96. 



Narrowly lanceolate with apices slightly rostrate-capitate, 30- 

 60^ long; pseudonodule distinct, often reaching to the margins; 

 pseudoraphe narrow, terminated by small nodules; striations 12-14 

 in 10 /t, distinctly punctate; girdle face linear, attenuated at the 

 ends. 



In ponds, lakes, rivers, etc. : Cedar Creek, Culbertson, Dismal River, 

 Grand Island, North Platte, Pelican Lake, Red Cloud, Seneca, Stromsburg. 

 Fossil : Loup City. 

 Devils Lake and fresh water near Devils Lake, N. Dak. ; Stockton, Cal. 



2. Synedra tenuissima Kiitz. BacilL, p. 64, pi. 14, fig. 6. 1844. 

 Frustulia tenuissima Kiitz. Syn. Diat., p. 24, pi. 2, fig. 22. 



1834- 

 Synedra acus Kiitz. BacilL, p. 68, pi. 30, fig. jo. 1844. 



PI. 3, figs. 97-104- 



Narrowly lanceolate with apices slightly rostrate-capitate, some- 

 times constricted in the middle and sometimes swollen, 45-230 /a 

 long; pseudoraphe narrow, striations distinct, 12-13 in 10 |U, usu- 

 ally lacking in the center, leaving a rectangular clear space. Very 

 variable, some forms like forms of .S". ulna, from which it can be 

 distinguished only by the finer striations. Some forms are de- 

 scribed as var. dclicatissima, fig. 97, and var. aiignstissima, figs. 

 98-^9. 



With Cladophora, Oscillatoria, Spirogyra, and other algae in tanks, 

 creeks, etc.: Cherry County, Crawford, Dewey Lake. Fremont, Heming- 

 ford, Holt County, South Bend, Ta'mage, Tecumseh, Valentine, Weeping 

 Water. 



Fossil : Greeley County, Spalding. 



Court Lake, Devils Lake, N. Dak. ; Cutmeat, S. Dak. ; Stockton, Cal. ; 

 Put-in Bay, Ohio. 



3. Synedra radians Kiitz. BacilL, p. 64, pi. 14, fig. 7. 1844. 

 PI. 3, figs. 105-114. 



Very narrowly linear-lanceolate, tapering toward the ends, some- 

 times capitate, 30-ico/A long; striations delicate, leaving a very 

 narrow pseudoraphe, 16-18 in 10 ^u.. usually lacking in the middle 

 of the valve, leaving a clear space. Deformed specimens have 



