Cytheridea (Haplocytheridea) plummeri 



Alexander 



Plate 2, Figures 9-11 



Cytheridea plummeri Alexander, 1929, Texas 

 Univ. Bull. 2907, p. 73, pi. 5, figs. 5-8. 

 Alexander and Alexander, 1933, Am. Mid- 

 land Naturalist, vol. 14, no. 3, p. 283, figs. 

 1-4. 

 Haplocytheridea ? plummeri (Alexander) 

 Schmidt, 1948, Jour. Paleontology, vol. 22, 

 p. 425, pi. 62, figs. 27-29 ; text fig. 2f . 

 Haplocytheridea ? sp. aff. H. ? plummeri (Alex- 

 ander) Swain, 1952, U. S. Geol. Survey Prof. 

 Paper 234-B, p. 79, pi. 8, fig. 15. 

 These specimens agree with Alexander's de- 

 scription. The species as illustrated by Alexander 

 shows anterior and postero-ventral spines. The 

 present specimens have about 12 sharp well- 

 defined spines along the anterior margin medially 

 and ventrally. About six sharp spines, angled pos- 

 teriorly, extend along the posterior third of the 

 ventral margin to the posterior acumination of 

 the right valve. Spines weak to absent on the left 

 valve. 



Left valve hinge consists of anterior and pos- 

 terior sockets connected by a crenulate groove 

 and separated from the dorsal margin by a well 

 developed accommodation groove (Ausweich- 

 furche) . Right valve consists of terminal notched 

 teeth separated by a narrow crenulate bar and ly- 

 ing above a shallow groove adjacent to the dorsal 

 margin. Musculature that of the genus. 



Dimensions : Fig. 9 : male ; length 0.80 mm ; 

 height 0.39 mm. 



Fig. 10 : female ; length 0.69 mm ; 

 height 0.40 mm. 



Occurrence: Peedee only, localities A and D. 

 U.S.N.M. 128976, 128977, 128978. 



Cytheridea (Haplocytheridea) wilmingtonensis 



Brown, n. sp. 



Plate 7, Figures 4-9 



Carapace in side view, ovate; left valve mark- 

 edly larger than right around entire periphery; 

 dorsal margin strongly convex; ventral margin 

 sinuous; anterior margin broadly rounded; pos- 

 terior margin less strongly rounded, extended ven- 

 trally; anterior margin weakly denticulate be- 

 low ; posterior margin with two to three weak 

 spines at postero-ventral junction. 



Surface of right valve: punctate, arranged in 

 vertical rows or weak furrows, medially ; posterior 

 fourth bears a short, bulbous sub-ventral ridge, 

 flanked anterad and posterad by short concave 

 furrows; post-medially is an irregular bulbous 

 ridge, anterad of which is a depressed area adja- 

 cent to the dorsal margin and containing one or 

 two irregularly oblique furrows which die out 

 medially. Surface of left valve : the anterior half 

 of this valve is the antithesis of the right valve, 

 the posterior third is smoothly convex lacking 

 the ridge and furrows of its right valve counter- 

 part. 



Muscle scar consists of four round spots in a 

 sub-vertical row located slightly antero-median, 

 forward of which are two more spots. Inner mar- 

 gin and line of concrescence coincide. Hingement 

 and musculature that of the genus. 



Dimensions: Holotype: length 0.57 mm; height 

 0.33 mm; biconvexity 0.25 mm. 



Occurrence: Peedee only, locality A. U.S.N.M. 

 128979, 128980, 128981, 128982, 128983, 128984. 



Remarks: In outline, arrangement of surface 

 ridges and furrows, and in internal features the 

 present specimens are judged to belong to the sub- 

 genus Haplocytheridea Stephenson. The degree 

 of overlap and strength of surface sculpture is 

 very variable with the locality but not within the 

 locality. The same variability is present in speci- 

 mens from various wells. The species is appar- 

 ently confined to the basal Peedee and should 

 make an excellent marker for picking the Peedee- 

 Black Creek contact. 



Cytheridea (Haplocytheridea) ulrichi (Berry) 

 Plate 2, Figures 4, 5 



Cythere ulrichi Berry, 1925, Am. Jour. Sci., 

 5th ser., vol. 23, no. 9, p. 483, fig. 3. 



Haplocytheridea ? ulrichi (Berry), Schmidt, 

 1948, Jour. Paleontology, vol. 22, p. 426, pi. 

 62, figs. 18, 19. 



Dimensions: Figure 4: male; length 0.61 mm; 

 height 0.33 mm; biconvexity 0.27 mm. 



Occurrence: Peedee only, localities A, B, C, D, 

 E, and F. U.S.N.M. 128985, 128986. 



Remarks : Internal and external features of this 

 species have been adequately described by 

 Schmidt, 1948. The hinge structure as described 

 by Schmidt is present in the North Carolina speci- 

 mens. The writer considers this hinge structure 



18 



