70 



Clarence J. Elmore 



gradually shortened toward the center, where they are entirely 

 lacking, leaving a large rectangular hyaline space, Ti-12 in 10 fi. 



In pools, ditches, etc. : Crete, Long Pine, Talmage. 



15. Navicula mesolepta Ehr. Amer., pi. 4, II, fig. 4. 1843. 

 Nazncula mesolepta Kiitz. Bacill., p. loi, pi. 28, fig. 75; pi. 30, 



fig. 34. 1844. 



PI. 8, figs. 267-269, 271-272; pi. 22, fig. 837. 



Lanceolate, triundulate with capitate ends, 22-62 ^u, long, 3-12 /x 

 wide ; costae radiate near the center, converging at the ends, lack- 

 ing in the center, leaving a transverse hyaline space, 10-15 in 10 /t. 

 The specimen represented in fig. 268 has shorter costae. 



In lakes, creeks, rivers, ponds, etc. : Dunning, Grand Island, Hackberry 

 Lake, Halsey, Lincoln, New Helena, O'Neill, St. Michael, Snake River, 

 Thedford, Trenton, Whitman. 



Fossil : Hay Springs, Merriman. 



Fresno, Cal. ; New Concord, Ohio. 



16. Navicula thermes (Ehr.) A. Schm. Atl., pi. 4^, figs. 67-71. 



1874. 

 Pinnularia thermes Ehr, Amer., pi. 2, VI, fig. 22. 1843. 

 Navicula nodulosa Kiitz. Bacill., p. loi, pi. 3, fig. 57 ; pi. 28, 



fig. 71. 1844. 

 Navicula interrupta W. Sm. Brit. Diat., I, p. 5?, is a synonym 



oi N. didyma Kiitz. 

 PI. 8, fig. 270; pi. 22, fig. 840. 



Linear with parallel or slightly concave margins and capitate 

 ends, 17-76 fjL long, 12-13^ wide; striations radiate near the center 

 and converging at the ends, extending nearly to the raphe at the 

 ends and gradually shortened toward the center, where they are 

 entirely lacking, forming a rhomboidal hyaline space, 9-15 in 10 fi. 



In rivers and pools: Ainsworth, Culbertson, Louisville, St. Paul, Thed- 

 ford. 

 Fossil : Thedford. 



17. Navicula legumen Ehr. Amer., pi. 4, I, fig. 17. 1843. 

 PI. 8, figs. 273-278. 



Linear or lanceolate, slightly triundulate, the undulations some- 



