ana and from the DeQueen Limestone at Gypsum 

 Bluff and Messers Creek, Arkansas. 



Length of holotype left valve 0.60 mm, height 

 0.42 mm, convexity of valve 0.20 mm. 



Occurrence. — DeQueen and Glen Rose Forma- 

 tions of southern Arkansas, northwestern Louisi- 

 ana, and northeastern Texas; beds of Trinity ( ?) 

 and pre-Trinity ( ?) age, subsurface of North 

 Carolina; beds of Trinity age in southern Okla- 

 homa and in the Kiamichi Formation (Freder- 

 icksburg Group) of northeastern Texas. The holo- 

 type is from the Glen Rose Formation, about 

 eight miles west of Weatherford, Parker County, 

 Texas. 



Asciocy there perforata (Vanderpool) 



Plate 4, Figures 5a-f; Text Figure 7c 



Pontocypris perforata Vanderpool, 1928, Jour. 



Paleont, v. 2, p. 102, pi. 14, figs. 9, 10. 



Howe and Laurencich, 1958, Introd. Study Cre- 

 taceous Ostracoda, p. 465, not text figure, 

 which is a copy of Vanderpool's Cypridea 

 tubercidata var. gypsum ensis (1928, pi. 13, 

 fig. 10). 



Shell features are as described earlier. The 

 hinge not previously described is as follows: in 

 left valve, hinge consists of an anterior short 

 crenulate socket, an interterminal weakly crenu- 

 late bar and a posterior crenulate socket; dorsal 

 to median portion of hinge is a prominent accom- 

 modation groove. Muscle scar a submedian verti- 

 cal row of four spots and two additional more 

 anterior spots. Inner lamellae moderately broad ; 

 line of concrescence and inner margin slightly 

 separated. Radial canals numerous both terminal- 

 ly and ventrally and in part have median bulbous 

 expansions. Ventral margin with prominent sel- 

 vage apophysis. 



Length of lectotype (PI. 4, Fig. 5a) 0.85 mm, 

 height 0.50 mm, convexity 0.43 mm. 



Remarks. — The hingement of the species is 

 that prescribed for Asciocy there, although the 

 general shape and posteroventral spinose exten- 

 sion are like Haplocytheridea. 



Occurrence. — Reported by Vanderpool to occur 

 commonly in the Glen Rose Formation of north- 

 eastern Texas and northern Louisiana and less 

 commonly in the DeQueen Limestone of southern 

 Arkansas. An externally closely similar though 

 not identical form was found in the Black Creek 

 and Eutaw equivalents of the North Carolina sub- 



surface (Swain, 1952, p. 79). That species is here 

 referred to Haplocytheridea lunarea Swain and 

 Brown, n. sp. 



Subfamily Eucytherinae Puri, 1954 



Genus Eucythere Brady, 1868 



Eucythere semiglypta Swain and Brown, n. sp. 



Plate 2, Figures lOa-f; Plate 3, Figures la, b 

 Text Figure 8b 



Shell elongate-subreniform to subtriangular- 

 acuminate ; dorsal margin moderately convex, 

 slightly angulate at position of greatest height 

 with steeper posterior than anterior slope; ven- 

 tral margin nearly straight, slightly concave me- 

 dially in right valve; anterior margin broadly 

 and uniformly curved; posterior margin narrow- 

 ly rounded and strongly extended to subacuminate 

 below; posteroventral submarginal bend of right 

 valve in part with a short spinose extension. Left 

 valve larger than right, overlapping and extend- 

 ing beyond the other around entire periphery. 

 Valves moderately convex, with greatest expan- 

 sion in posterior third. 



Ornamentation consists principally of irregu- 

 lar closely spaced grooves in posterior third; 

 grooves are branching and anastomosing, longi- 

 tudinally arranged in ventral part, and sweeping 

 upward in dorsal part of valve ; grooved surface 

 appears irregularly nodose ; anterior half of shell 

 varies from smooth to weakly pitted, and with 

 low, irregular, roughly-longitudinal ridges in 

 some specimens. 



Hinge of right valve formed of the ridgelike 

 extension of dorsal edge of valve which fits into 

 corresponding groove in edge of anterior half of 

 left valve; at position of greatest height, right 

 valve ridge is interrupted by a small notch. Hinge 

 of left valve consists, in anterior half, of a groove 

 for reception of edge of right ; ventrad of groove, 

 beginning at midlength and extending to about 

 one-fourth from anterior end, is a strong ridge 

 process which has a blunt anterior termination. 

 Posterior to position of greatest height, hinge 

 edge of left valve fits over edge of right without 

 further articulation. 



Muscle scar consists of an anteromedian verti- 

 cal, slightly curved row of four closely spaced 

 spots and two additional spots lying anterior to 

 the upper and lower ends of main group; upper 

 of the two spots horseshoe-shaped or double. In- 

 ner lamellae moderately broad anteriorly, nar- 



27 



