TJic Diatoms of Nebraska I23 



Culbertson, Dismal River, Dunning, Fairbury, O'Neill, Tekamah, St. Paul, 

 Thedford. 



Fossil : Agate, Hay Springs, Loup City, Thedford. 



Rapid Cit3^, S. Dak. ; Ft. Collins, Colo. 



2. Encyonema turgidum (Greg.) Grun. in A. Schm. Atl., pi. 10, 



figs. 40-53. 1874. 



Cymhella turgida Greg, in Mic. Jour., p. 5, pi. i, fig. 18. i8f,6. 



PI. 17, figs. 625-627. 



Lanceolate, 50-100/* long, 12-23 /i, wide, dorsal margin ver}- 

 convex, ventral margin nearly straight or more or less convex, 

 apices acute ; raphe straight, ahout twice as far from the dorsal as 

 from the ventral margin ; terminal nodules near tlie ends ; stri- 

 ations nearly perpendicular to the margins or slightly converging 

 at the ends on the ventral side, 7-9 in lO/*, rather coarsely granu- 

 lar, extending nearly to the raphe, leaving a distinct but narrow 

 space along the raphe, only slightly wider in the center. 



In creeks, rivers, lakes, ponds, etc., with Spirogyra, Vaucheria, Con- 

 ferva, or Oscillatoria, also fossil : Arago, Ashland, Auburn, Benk'.eman, 

 Bratton, Brock, Broken Bow, Central City, Culbertson, Dewey Lake, Dis- 

 mal River, Emerald, Fremont, Grand Island, Long Pine, North Platte, 

 Orleans, Pleasant Dale, Ruby, St. Michael, St. Paul, Scottsbluff, Seneca, 

 Seward, Snake River, South Bend, Talmage, Trenton, Valentine, Wahoo, 

 Weeping Water, West Point, Whitman. 



Fossil: Agate, Cherry County, Mullen, Thedford. 



Cheyenne, Wyo. ; Blackpipe, Rapid City, S. Dak. ; Stockton, Cal. ; Em- 

 poria, Kansas. 



3. Encyonema ventricosum (Ag.) Grun. in Kirchn. Alg. Schles., 



p. 189. 1878. 



Cymhella ventricosa Ag. Consp., I, p. p. 1830. 



Encyonema caespitosmn Kiitz. Spec. Alg., p. 61. 1849. 



PI. 17, figs. 628-629. 



Naviculoid, 15-36 /x long, 7-12 ^ wide, dorsal margin much more 

 convex than the ventral, which is often gibbous ; apices slightly 

 acute, often bent toward the ventral side; raphe straight; terminal 

 nodules near the ends of the valves ; striations nearly perpendicular 

 to the margins of the valves, 9-16 in 10 /a, extending nearly to the 

 raphe, leaving a very narrow axial area. Fig. 629 is from Raben- 

 horst's Alg. Eu., 1636. 



