40 



CHESTER OSTRACODES OF ILLINOIS 



Paint dreek formation, locality 2, rare; 

 Vienna formation, locality 10, rare; Men- 

 ard formation, locality 28, common, 



Pennsylvanian species found in both Illi- 

 nois and the mid-Continent area show that 

 the genus Coriiigella is quite variable. The 

 Chester species, illustrated here by an adult 

 from the Paint Creek is known also from 

 the Golconda, Vienna and Menard forma- 

 tions. The mature specimen is almost indis- 

 tinguishable from many elongate, short- 

 spined species occurring abundantly in 

 samples yielding many specimens of the 

 Pennsylvanian C. minuta — C. longispina 

 type. The only known differentiation is 

 by means of the large form ratio (1.87) of 

 the Chester series. 



Family Glyptopleuridae Girty 

 Genus Glyptopleura Girty 

 Glyptopleura alata 

 Croneis and Funkhouser 

 Plate 6, figures 45-47 

 Glyptopleura alata Cronies and Funkhouser, 1938, 

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

 p. 349, pi. 10, fig. 3, Clore formation. 

 Glyptopleura skathiae Coryell and Johnson, 1939, 

 Jour. Paleontology, vol. 13, p. 217, pi. 25. fig. 

 4, Clore formation. 



Length, 0.95 mm; height, 0.59 mm; 

 thickness, 0.40 mm. 



Clore formation, locality 26, common. 



This common Clore species is character- 

 ized by its almost horizontal ribs and by its 

 short ovate outline. 



Glyptopleura alvea Cooper, n. sp. 



Plate 6, figures 31-33 



Carapace ovate, hinge long, straight ; dor- 

 sum trough-like, very broad ; three fairly 

 prominent ribs, central one traversing an 

 elongate pit; less distinct ribs occur be- 

 tween more prominent ones, one above and 

 two below pit ; dorsal angles sharp. 



Length, 1.13 mm; height, 0.71 mm; 

 thickness, 0.55 mm. 



Kinkaid formation, locality 5, rare. 



Glyptopleura Bristol: 



Croneis and Gutke 



Plate 6, figure 38 



Glyptopleura bristoli Croneis and Gutke, 1939, 

 Bull. Denison Univ., Jour. Sci. Lab., vol. 34, 

 p. 49, pi. 2, figs. 3, 4, Clore formation. 



Glyptopleura pergihha Croneis and Gutke, 1939, 

 idem., p. 53, pi. 2, figs. 1, 2, Clore formation. 



Length, 0.96 mm; height, 0.55 mm. 

 Renault formation, locality 25, rare; 

 Paint Creek formation, locality 2, rare. 



Glyptopleura circumcostata 



Cooper, n. sp. 



Pate 7, figures 1-3 



Carapace large, elongate, ends rounded; 

 hinge straight ; posterior dorsal angle sharp ; 

 hinge depressed, with notched overlap at 

 each end ; ribs form triple U nested one 

 inside the other, joined at the base; two 

 additional unjoined ribs inside Inner U and 

 below pit; cardinal area broad, shal- 

 lowly V-shaped where hinge is slightly 

 depressed. 



Length, 1.06 mm; height, 0.64 mm; 

 thickness, 0.54 mm. 



Kinkaid formation, locality 3, common. 



Glyptopleura complexa 



Croneis and Bristol 



Plate 7, figure 32 



Glyptopleura comlexa Croneis and Bristol, 1939, 

 Bull. Denison Univ., Jour. Sci. Lab., vol. 34, 

 p. 87, pi. 4, fig. 25, Menard formation. 



Glyptopleura hamatilis Croneis and Bristol, 1939, 

 idem., p. 88, pi. 4, fig. 22, Menard formation. 



Length, 0.71 mm; height, 0.42 mm. 



Vienna formation, locality 10, rare; Men- 

 ard formation, locality 28, depth 746-49 

 feet, common ; Clore formation, locality 28, 

 rare; Kinkaid formation, locality 5, rare. 



Glyptopleura elongata Cooper, n. sp. 

 Plate 7, figure 42 



Carapace long, about symmetrical in out- 

 line, ends rounded, hinge straight, short 

 compared to total length ; four ribs implant- 

 ed in broad U, second from dorsum inter- 

 rupted by pit; linear dimension greatly in- 

 creased by comparative elongation of 

 posterior end, observable by comparison 

 w^ith the posterior dorsal angle; hinge only 

 slightly more than half total length of shell. 



Length, 1.14 mm; height, 0.53 mm. 



Clore formation, locality 26, rare. 



Glyptopleura henbesti 



Croneis and Gutke 



Plate 7, figure 9-11 



Glyptopleura henbesti Croneis and Gutke, 1939, 

 Bull. Denison Univ., Jour. Sci. Lab., vol. 34, 

 p. 51, pi. 2, figs. 7, 8, Renault formation. 



Glyptopleura hendricksi Croneis and Gutke, 1939, 

 idem., p. 52, pi. 2, figs. 5, 6, Renault forma- 

 tion. 



