BARIDIIDAE 



29 



greatest length and thickness central ; over- 

 lap moderately developed, varies little 

 around the entire margin. 



Length 0.42 mm; height, 0.23 mm; 

 thickness, 0.18 mm. 



Paint Creek formation, locality 24, depth 

 2454 feet, common. 



Bythocypris opima Cooper, n. sp. 

 Plate 3, figures 20-21 



Carapace subovate, tumid; overlap indis- 

 tinct, except on ventral margin, which is 

 slightly concave ; greatest thickness slightly 

 back of middle, greatest height above center ; 

 posterior margin almost vertical, surface 

 smooth. 



Length, 0.82 mm; height, 0.51 mm; 

 thickness, 0.33 mm. 



Golconda formation locality 22, rare. 



Bythocypris ovata Cooper, n. sp. 

 Plate 3, figures 11-13 



Carapace small, bean-shaped, smooth ; 

 ends and dorsum rounded ; greatest height 

 slightly posterior ; greatest thickness central ; 

 greatest length in lower half of shell ; over- 

 lap prominent, especially along dorsum. 



Length, 0.69 mm; height, 0.44 mm; 

 thickness, 0.31 mm. 



Paint Creek formation, locality 21, depth 

 1304-1323 feet, common. 



Bythocypris truncata Cooper, n. sp. 

 Plate 3, figures 22-28 



Carapace reniform ; dorsum highly arched 

 and asymmetrical, posterior slope longer, 

 venter straight to concave; ends rounded; 

 greatest length well below center; greatest 

 thickness almost central, surface sloping 

 gradually in smooth convex curve to broad 

 dorsum and posterior end, more rapidly to 

 venter and anterior, giving distinctly acu- 

 minate appearance to latter margins, over- 

 lap left over right, most prominent along 

 venter and adjacent parts of terminal mar- 

 gins, surface smooth. 



Holotype, length, 0.98 mm; height, 0.65 

 mm; thickness, 0.50 mm. 



Renault formation, locality 25, common. 



Genus Cribroconch A Cooper, n. gen. 



Seminolites (?) (in part) Harlton, 1929, Am. 

 Jour. Sci., ser. 5, vol. 18, p. 266. — Harlton, 

 1933, Jour. Paleontology, vol. 7, p. 27. 



Small ovate ostracodes with arched dor- 

 sum, straight to slightly convex venter; 

 overlap, right over left around entire margin 

 except on postero-dorsal slope where artic- 

 ulation is somewhat indented ; anterior end 

 curved to acuminate ; posterior somewhat 

 acuminate to rounded in lateral view ; post- 

 ero-lateral slope bears transverse ridge or 

 carina more or less perpendicular to long 

 axis of shell which may be terminated above 

 and below in short, sharp spines, directed 

 backward ; postero-dorsal slope flattened ; 

 surface marked by numerous irregularly 

 spaced, relatively large, round pores. 



Genotype. — C. costata n. sp., Renault 

 formation. 



Cribroconcha is flattened antero-dorsally 

 like Healdia but the latter lacks the round 

 perforations similar to those of Seminolites. 

 Criboconcha lacks the anterior rib of Sem- 

 inolites and has, instead of a curved posterior 

 rib a straight, spine-terminated rib. Many 

 species of Healdia carry the short spines at 

 the ends of the posterior rib but all seem to 

 lack the very definite perforations character- 

 istic of Cribroconcha and Seminolites. 



Cribroconcha costata Cooper, n. sp. 

 Plate 3, figures 37-42 



Carapace small, ovate in lateral outline ; 

 dorsum arched, venter straight; postero- 

 dorsal slope low, hinge line incised ; postero- 

 lateral slope interrupted by straight, vertical 

 to slightly inclined rib terminated at each 

 end by backward-directed spine; rib bor- 

 dered by slight sinus; surface perforated by 

 numerous round, deep pits, irregularly 

 spaced ; antero-ventral angle sharp ; wedge- 

 shaped in dorsal view; anterior end acum- 

 inate, posterior margin irregular. 



Holotype, length, 0.50 mm; height, 0.30 

 mm ; thickness, 0.23 mm. 



Renault formation, locality 9, common ; 

 Paint Creek formation, localties 24 and 28, 

 common. 



This species differs from C. perforata 

 (Harlton) and C. conspicua (Harlton) in 

 having an arched rather than a smoothly 

 convex dorsum, and in possessing a sharp 

 antero-dorsal angle as compared to the 

 rounded anterior end of the latter species. 

 Harlton (1929, p. 266) states in his des- 

 cription of the above species that a faint 



