90 



CHALMER L. COOPER 



smaller than two near the dorsum. The 

 only other Chester species, C. golcondensis 

 (Croneis and Gale), is considerably more 

 elongate. 



Kinkaid formation, bed 1, Johnson 

 County, Illinois 



Genus Varix Cooper, n. gen. 



Carapace subovate, cardinal angles sub- 

 equal, with well-defined "swing," free mar- 

 gin (and part of dorsal margin) bordered by 

 a well-defined ridge, central portion marked 

 by irregular, more or less continuous ridges. 



Genotype, Varix propria Cooper n. sp. 



Varix conforms to other genera of the 

 family in its shape and bordering ridge, but 

 the irregularity of its other ornamental fea- 

 tures distinguishes it from its near relatives. 



Varix propria Cooper, n. sp. 

 Plate 23, figures 12-14 



Carapace elongate, subovate, hinge line 

 straight, ends rounded, ventral margin 

 slightly concave; cardinal angles very un- 

 equal, the anterior being about 90°, the 

 posterior markedly acute; free margins and 

 part of dorsal margin bordered by a promi- 

 nent ridge of uniform height and width; 

 central portion of shell marked by an ir- 

 regular ridge of similar character, sub- 

 rectangular to subelliptical, the axis of 

 "ellipse" parallel to ventral margin, with a 

 continuation of the ridge inside the "ellipse" ; 

 one side of the central portion of the ridge 

 develops into a loop anterior to a shallow 

 circular pit located near midlength; the 

 loop ends posterior to the pit in a small 

 circular node; near the center of the antero- 

 dorsal margin the outer loop rises above the 

 hinge line; articulation simple and appar- 

 ently without overlap. 



Length (of holotype), 0.49 mm.; height, 

 0.38 mm.; form ratio, 1.44. 



Kinkaid formation, bed 5, Johnson 

 County, Illinois. 



Family Glyptopleuridae Girty, 1910 



Genus Glyptopleura Girty, 1910 



Glyptopleura similis Croneis and 



Funkhouser 



Plate 22, figures 32-34 



Glyptopleura similis Croneis and Funkhouser, 

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



S3, p. 352, pi. 10, fig. 4.— Cooper, 1941, pi. 7, 

 figs. 23, 24; Clore formation, Illinois. 



This species has a rib pattern somewhat 

 similar to G. coryelli Harlton in that the rib 

 which is just above the pit bifurcates ante- 

 riorly. However, the two species may be 

 distinguished by their differences in lateral 

 outline, the Pennsylvanian species being 

 more quadrate, or not as subelliptical as in 

 G. similis. 



Kinkaid formation, beds 4-6, Johnson 

 County, Illinois. 



Family Healdiidae Harlton, 1933 



Genus Healdia Roundy, 1926 



Healdia sulcata Cooper, n. sp. 



Plates 22, figures 2-4 



Carapace short, tumid, lateral outline 

 subelliptical; dorsal margin strongly convex, 

 ventral margin nearly straight; posterior 

 ridge curved and directed strongly toward 

 posterior, rising but little above curvature 

 of shell as seen in dorsal view; ridge bordered 

 on anterior side by a deeply incised semi- 

 circular furrow of uniform width; overlap 

 prominent around dorsal and ventral mar- 

 gins, each valve developed at ends to pro- 

 duce a slightly incised articulation poste- 

 riorly and in irregular flare or "frill" on 

 anterior; surface smooth except for furrow. 



Length, 0.52 mm.; height, 0.36 mm.; 

 thickness, 0.29 mm. 



77. sulcata is readily distinguished by the 

 unusual furrow in front of the usual poste- 

 rior ridge which is typical of the genus. 

 However, t'his should not be confused with 

 the depressed area of Incisurella or the 

 trough formed by a row of pits in Cribro- 

 concha. Except for the furrow H. sulcata 

 is much like many other species such as H. 

 ornata Morey and H. ovoidea Cooper from 

 the Chester and H. ehlersi Bradfield and H. 

 nucleolata Knight from the Pennsylvanian. 



Kinkaid formation, beds 4-6, Johnson 

 County, Illinois • 



Family Kirkbyidae Ulrich and 



Bassler, 1923 



Genus Ectodemites Cooper, 1941 



ECTODEMITES TUMIDUS Cooper 



Plate 21, figures 14-16 



Ectodemites tumidus Cooper, 1941, Illinois Geol. 

 Survey Rept. Inv. 77, p. 51, pi. 10, figs. 1-3. 



E. tumidus, known only from the Kinkaid, 



