58 Clarence J. Elmore 



chromatophores small, plate-like ; aiixospore one from two mother 

 cells. 



A. Cells united in filaments. 



b. Rostrate-capitate. i. E. arcus. 



bb. Scarcely capitate. 2. E. major. 



AA. Cells not united in filaments. 

 b. Slightly arcuate. 



c. With slight median enlargement. 3. E. formica, 



cc. With no median enlargement. 4. E. lunaris. 



bb. More or less wrinkled. 



c. With two dorsal swellings. 5. E. diodon. 



cc. With several dorsal swellings. 6. E. robusta 



ccc. With both dorsal and ventral swellings. 7. E. eriica. 



1. Eunotia arcus Ehr. Inf.^ p. ipi. 1838. 

 PI. 5, fig. 149; pi. 22, figs. 819-820. 



Curved, 30-90 /a long, ends capitate, often only slightly so, ven- 

 tral margin straight or slightly concave, dorsal margin convex and 

 sometimes undulate, constricted on the dorsal margin near the 

 ends; striations punctate, 12-15 in lO/x. 



Cody Lake, Columbus, Culbertson, Scottsbluff, Thedford. 

 Fossil : Greeley County, Loup City, Mullen. 



2. Eunotia major (W. Sm.) Rabenh. Fl. En. Alg., I, p. '/2. 



1864. 

 Hiniantidium luajus W. Sm. Brit. Diat., II, p. 14, pi. jj, fig. 



286. 1856. 

 PI. 5, figs. 150-152. 



Arcuate with parallel margins, 62-190 ^a long, ends obtusely 

 rounded, sometimes capitate; striations finely punctate, 9-12 in 



10 fX. 



Clear Lake, Dismal River, Dunning, Hackberry Lake, Long Pine, Thed- 

 ford, Whitman, Woodlake. 



Fossil : Agate, Cherry County, Merriman, Mullen. 



3. Eunotia formica Ehr. Vcrh., p. 126. 1843. 

 PI- 5. figs. 153-155- 



Arcuate, 70-162 /x long, 8-14 fx wide, width practically the same 

 throughout the entire length ; apices rounded or triangular-acute ; 

 ventral side gibbous in the middle, dorsal side slightly inflated, 



