60 



CHESTER OSTRACODES OF ILLINOIS 



prominent on postero-ventral margin ; sulcus 

 deep, connected with cardinal area by low 

 saddle ; greatest length diagonal from upper 

 posterior to lower anterior end ; shallow fur- 

 row or flattening of shell convexity borders 

 free margin ; hinge deeply incised ; surface 

 finely granulose. 



Length, 0.75 mm; height, 0.46 mm; 

 thickness, 0.37 mm. 



Paint Creek formation, locality 24, depth 

 2454 feet, abudant. 



Sansabella harrisi 

 Croneis and Funkhouser 

 Plate 13, figures 15-16 

 Sansabella harrisi Croneis and Funkhouser, 1938, 

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

 p. 334, pi. 9, figs. 7, 8, Clore formation. 

 Lamarella thurmani Croneis and Funkhouser, 

 1938, idem., p. 336, pi. 9, figs. 11, 12, Clore 

 formation. 



Length, 0.69 mm ; height, 0.44 mm ; 

 thickness, 0.33 mm. 



Clore formation, locality 26, rare; Kin- 

 kaid formation, locality 5, common. 



L. thurmani is apparently a mashed speci- 

 men of S. harrisi. 



Sansabella lenticularis Cooper, n. sp. 

 Plate 13, figures 11-12 

 Carapace elongate, lens-shaped in dorsal 

 outline; hinge straight, channeled, with 

 notches at ends; greatest thickness central; 

 anterior extremity below and posterior ex- 

 tremity above midheight ; prominent sinus 

 just in front of midpoint; postero-ventral 

 truncation marked ; overlap prominent 

 around free margin ; a short node located 

 in postero-dorsal corner of left valve; 

 surface smooth. 



Length, 0.63 mm; height, 0.38 mm; 

 thickness, 0.28 mm. 



Clore formation, locality 4, rare. 



Sansabella njorthi 

 (Coryell and Johnson) 

 Reversahella njorthi Coryell and Johnson, 1939, 

 Jour. Paleontology, vol. 13, p. 221, pi. 26, 

 fig. 8, Clore formation. 

 Persansabella njorthi. Sohn, 1040, idem., vol. 14, 

 p. 159. 



Sansabella ovata Cooper, n. sp. 

 Plate 13, figures 52-53 

 Carapace thick, ovate in lateral and dorsal 

 views; ends rounded, dorsum slightly con- 



vex; forward swing very slight; overlap- 

 prominent; sulcus deep in lower part, be- 

 coming abruptly shallower upward toward 

 dorsum; hinge straight and deeply chan- 

 neled between notches; greatest thickness 

 posterior, although but slightly greater than 

 at anterior end ; surface smooth. 



Length, 0.66 mm ; height, 0.44 mm ; 

 thickness, 0.31 mm. 



Paint Creek formation, locality 24, depth 

 2454 feet, common. 



This species is distinguished by the reg- 

 ularity of the dorsal and lateral outlines and 

 by the relative thickness of the shell. 



Sansabella parallela Cooper, n. sp. 



Plate 13, figures 42-43 



Carapace somewhat rectangular, venter 

 almost straight, parallel to dorsum ; anterior 

 and posterior extremities above and below 

 midheight respectively; hinge straight, very 

 shallowly channeled, terminated at either 

 end by prominent overlapping notch ; sinus 

 deep, fairly broad ; posterior half tumid ; 

 small node in postero-dorsal angle of the 

 right valve ; surface smooth ; overlap promi- 

 nent, especially along venter. 



Length, 0.72 mm ; height, 0.42 mm ; 

 thickness, 0.32 mm. 



Vienna formation, locality 10, rare. 



Sansabella truncata Cooper, n. sp. 



Plate 13, figures 36-41 



Carapace thick, subovate in lateral view, 

 dorsum straight, ends rounded ; venter 

 strongly curved, swinging anteriorly into 

 anterior margin in flat curve, giving a 

 somewhat truncated appearance and a 

 strong anterior swing in lateral view ; sulcus 

 elongate, deep, forward of center ; overlap 

 very prominent around free margins, espe- 

 cially venter ; greatest height central ; great- 

 est length diagonal across shell from above 

 center posteriorly to below center anterior- 

 ly; hinge straight, distinctly channeled be- 

 tween notches; short spine sometimes lo- 

 cated in posterior cardinal angle ; surface 

 smooth or finely granulose. 



Length, 0.73 mm ; height, 0.45 mm ; 

 thickness, 0.40 mm. 



Golconda formation, locality 22, com- 

 mon. 



