46 Clarence J. Elmore 



punctate, 10-12 in 10 /a; girdle face narrow, showing from 2 to 4 

 false septa. 



Atkinson, 



Fossil : Mullen. 



Chippewa Falls, Wis. ; Stockton, Cal. 



9. Denticula 



Denticula Kiitz. BacilL, p. 4J. 1844. em. Grun. in Wien. 

 Verh., XII, p. 546. 1862. 



Etym,, diminutive of Lat. dens, tooth, on account of the tooth- 

 like ribs. 



Valves lanceolate, without raphe, with a row of transverse septa 

 appearing like ribs, between which are transverse granular or 

 pearl-like striations ; rectangular in girdle view ; transverse ribs 

 capitate, reaching to the girdle; cells free, single or united in 

 short filaments. 



A. Apices obtuse. I. D. elegans. 



AA. Apices acute. 2. D. tenuis. 



1. Denticula elegans Kiitz. BacilL, p. 14, pi. 17, fig. 5. 1844. 

 PI. 2, figs. 40-43- 



Cells linear-lanceolate with apices obtusely rounded, 20-35 |U 

 long; carina obscure; 2.5-5 costae in 10 /x; striations distinct, 

 coarsely punctate, 15-17 in 10 /a ; girdle face very broad, rectangu- 

 lar with rounded angles showing the capitate apices of the costae. 

 A curved form is shown in fig. 41. 



With Spirogyra, etc.: Andrews, Anselmo, Benkleman, Cairo, Clear Lake. 

 Crawford, Dunning, Grand Island, Lakeside, Long Pine, North Platte, 

 Northport, Rupert, St. Paul, Seneca, Sheridan County, Snake River, 

 Thedford, Trenton, Valentine. 



Fossil: Agate, Cherry County, Mullen. 



Blackpipe, Cutmeat, Rosebud, Turtle River, S. Dak. ; Devils Lake, N 

 Dak. ; Cheyenne, Wyo. 



2. Denticula tenuis Kiitz. BacilL, />. 43. 1844. 

 PI. 2, figs. 44-46. 



Cells lanceolate, 15-45/* long, with apices attenuate to rostrate; 

 carina conspicuous; costae 3-8 in 10 ju.; striations fine, 15-17 i^ 



