DREPANELLIDAE 



39 



the female as contrasted with the male 

 (fig. 21), while the lateral views (figs. 20 

 and 22) are indistinguishable one from the 

 other. 



Sargentina asulcata Cooper, n. sp. 

 Plate 6, figures 1-2 



Carapace subelliptical, tumid ; surface 

 smooth; overlap prominent around entire 

 margin; ends almost equally curved except 

 for slight backward swing; greatest thick- 

 ness slightly in front of middle, greatest 

 length and height through center ; right 

 valve has broad, somewhat flat area in 

 postero-dorsal region, beginning just below 

 hinge ; hinge line straight, meeting posterior 

 margin at an angle with pronounced over- 

 lap of right valve. 



Length, 0.89 mm; height, 0.62 mm; 

 thickness, 0.45 mm. 



Kinkaid formation, locality 5, rare. 



S. asulcata differs from all other species 

 in the lack of a prominent sulcus, in lieu 

 of which is found the flattened area in the 

 mid-dorsal portion of the left valve. 



Sargentina crassimarginata 



(Croneis and Thurman) 



Plate 6, figures 9-10 



Sulcella crassimarginata Croneis and Thurman, 

 1938, Bull. Denison Univ., Jour. Sci. Lab., 

 vol. 33, p. 328, pi. 7, figs. 15, 16, Kinkaid 

 formation. 



Carapace subelliptical in lateral outline; 

 right valve overlaps prominently around 

 entire margin, especially along dorsum and 

 venter ; dorsal margin of left valve straight, 

 lateral outline with forward swing; sulcus 

 deep, forward of center; hinge straight, 

 notched at ends ; surface smooth. 



Length, 0.73 mm; height, 0.51 mm; 

 thickness, 0.33 mm. 



Kinkaid formation, locality 5, rare. 



This form lacks the lateral configuration 

 and type of overlap of Sulcella and also 

 possesses a deeper sulcus than is present in 

 the latter genus. 



Genus Sulcella Coryell and Sample 



Sulcella celsa Cooper, n. sp. 



Plate 6, figures 15-16 



Carapace ovate, ends high and rounded, 

 dorsum and venter curved ; sulcus and ter- 

 minal ridges indistinct ; hinge line curved ; 

 overlap greatest along dorsum and venter ; 

 surface smooth. 



Length, 0.73 mm; height, 0.44 mm; 

 thickness, 0.40 mm. 



Paint Creek formation, locality 24, depth 

 2454 feet, common. 



S. celsa is differentiated from S. ovata 

 n. sp. by its low form ratio, 1.65 as compared 

 to 1.8. 



Sulcella nodocosta Cooper, n. sp. 

 Plate 6, figures 13-14 



Carapace ovate, ends round ; dorsum 

 curved, venter almost straight ; overlap mod- 

 erate on dorsum and venter, inconspicuous 

 on ends; sulcus very indistinct, wide, shal- 

 low ; anterior ridge low, parallel to margin ; 

 posterior ridge more prominent, higher at 

 ends than in middle, giving somewhat knob- 

 like appearance, especially in the dorsal 

 view ; hinge slightly sinuous ; surface 

 smooth. 



Length, 0.58 mm; height, 0.35 mm; 

 thickness, 0.22 mm. 



Paint Creek formation, locality 24, depth 

 2454 feet, common. 



This species may be distinguished from 

 S. ovata n. sp. by the raised and abruptly 

 terminated posterior costae. 



Sulcella ovata Cooper, n. sp. 

 Plate 6, figures 11-12 



Carapace ovate; venter straight, dorsum 

 curved ; ends rounded ; overlap most prom- 

 inent on dorsum and venter ; sulcus central, 

 wide, very shallow; terminal ridges quite 

 inconspicuous; hinge line curved; greatest 

 thickness in center of posterior half; sur- 

 face smooth. 



Length, 0.72 mm; height, 0.42 mm; 

 thickness, 0.29 mm. 



Paint Creek formation, locality 24, depth 

 2454 feet, common. 



Family Drepanellidae Swartz 

 Genus CoRNiGELLA Warthin 



CORNIGELLA GOLCONDENSIS 



(Croneis and Gale) 

 Plate 6, figures 36-37 



Verrucosella golcondensis Croneis and Gale, 1938, 

 Bull. Denison Univ., Jour. Sci. Lab., vol. 33, 



p. 275, pi. 5, fig. 8, Golconda formation. 



Croneis and Bristol, 1939, ibid., vol. 34, p. 

 85, pi. 4, fig. 6, Menard formation. 



Length, 0.67 mm; height, 0.36 mm; 

 thickness, 0.27 mm. 



