I20 Clarence J. Elmore 



PI. i6, figs. 607-610; pi. 23, fig. 856. 



Lunate, 80-2 18 /a long, 16-32 /x wide, ventral margin slightly 

 concave, usually gibbous in the middle, apices obtuse ; raphe arcu- 

 ate with ends bent toward the dorsal side; striations nearly per- 

 pendicular to the margins, 6-10 in 10 /x on the dorsal side in the 

 middle, closer elsewhere, composed of fine dots extending nearly 

 to the raphe, leaving a very narrow space which is slightly wider 

 opposite the central nodule. 



In creeks, rivers, ponds, etc., also fossil: Andrews, Broken Bow, Cedar 

 Creek, Chadron, Crawford, Dewey Lake, Dismal River, Grand Island, 

 Hackberry Lake, Halsey, Norfolk, North Platte, Oakdale, St. Michael, 

 Scottsbluff, Seneca, Stanton, Thedford, Valentine, Wann, West Point, 

 Woodlake. 



Fossil: Agate, Cherry County, Greeley County, Hay Springs, Loup City, 

 Mullen, Thedford, Valentine, Williams's Canyon. 



Stockton, Cal. ; Ft. Collins, Colo. ; Blackhand, Put-in Bay, Ohio. 



11. Cymbella parva W. Sm. 1852 according to Cleve Syn. Nav. 



Diat., I, p. 1^2. 



Cocconcina parvum W. Sm. Brit. Diat., I, p. 76, pi. 2^, fig. 

 222, and pi. 24, fig. 222. 185^. 



PI. 16, figs. 611-612. 



Lunate, 30-57 /x long, 9-12 /a wide, ventral margin slightly con- 

 cave, usually gibbous in the middle, apices obtuse ; raphe arcuate 

 with ends bent toward the dorsal side ; striations nearly perpen- 

 dicular to the margins, 8-10 in 10 /a on the dorsal side and 12-13 

 on the ventral side in the middle, closer toward the ends, extending 

 nearly to the raphe, leaving a very narrow hyaline space which is 

 very slightly larger opposite the central nodule. 



Grand Island, Lakeside, New Helena, North Platte, St. Paul, Thedford. 

 Valentine. 



Fossil : Hay Springs, Valentine. 



Devils Lake and fresh water near Devils Lake, N. Dak.; Cutmeat, 

 Rapid City, S. Dak. 



12. Cymbella cymbiformis Ag. Consp.. p. 10, iS:;2. (Accord- 



ing to Kiitc. Syn. Diat., p. 11.) 

 PI. 16. figs. 613-615. 

 Lunate with nearly straight, sometimes slightly gibbous ventral 



