medially; anterior margin broadly and .evenly 

 rounded, weakly rimmed below ; posterior margin 

 less broadly rounded ; right valve larger than left 

 around entire periphery, more pronounced dor- 

 sally and ventrally; widest post-medially, highest 

 in posterior fourth. 



Medially, the valves show a system of clearly 

 denned, closely spaced, wedge-shaped furrows out- 

 lined by fine subdued ridges which show a sub- 

 parallel to anastomosing arrangement; anterior 

 and posterior thirds smooth, surface glassy. 



Dimensions : Holotype : length 0.63 mm ; height 

 0.35 mm; biconvexity 0.18 mm. 



Occurrence : Peedee only, localities A, C, and F. 

 U.S.N.M. 128902, 128903, 128904. 



Remarks: The outline, valve overlap, faint an- 

 terior rim and internal features of this species 

 are suggestive of the genera Cytherella Jones and 

 Cytherelloidea Alexander. Because of the median 

 surface sculpture which resembles arachaic 

 wedge-shaped writing the specimens are believed 

 to be closer to Cytherelloidea Alexander and are 

 provisionally placed in that genus. 



Cytherelloidea sohni Brown, n. sp. 



Plate 2, Figures 1-3 



Shell in side view, subquadrate ; dorsal margin 

 sinuate, convex medially ; ventral margin straight, 

 slightly concave medially ; anterior margin broad- 

 ly rounded ; posterior margin rounded. 



Anterior, ventral, and posterior margins sharp- 

 ly rimmed by a continuous connecting ridge rising 

 at anterior dorsal angle. At posterior dorsal angle 

 the ridge swings gently inward subparallel to the 

 dorsal margin, terminating below the anterior 

 dorsal angle and outlining, dorsally, a shallow sub- 

 central pit. Between the pit and ventral margin 

 are two short ridges, slightly concave upward, and 

 merging at their ends into the posterior and an- 

 terior-third of the valves. 



Dimensions : Holotype : length 0.57 mm ; height 

 0.29 mm; biconvexity 0.19 mm. 



Occurrence : Peedee only, localities A, C, and E. 

 U.S.N.M. 128905, 128906, 128907. 



Remarks : This species which has not been rec- 

 ognized in well cuttings south of the Neuse River 

 seems to be an excellent subsurface guide in the 

 northeastern part of the State. Named for I. Greg- 

 ory Sohn, U. S. Geological Survey. 



Cytherelloidea greenensis Brown, n. sp. 



Plate 1, Figures 22, 23, 26, 29 

 Carapace in lateral view, oblong-ovate; dorsal 



margin straight to weakly convex; ventral mar- 

 gin straight; anterior margin broadly and evenly 

 rounded ; posterior margin less broadly rounded. 



Anterior margin with well-defined rim ; ventral 

 margin less strongly rimmed ; above posterior mar- 

 gin and parallel to it are prominent well-defined 

 dorsal and ventral tubercles connected by a short 

 sharp ridge ; a sharp ridge extends from the ven- 

 tral tubercle, anteriorly, parallel to and above the 

 ventral margin, terminating sharply in flat ante- 

 rior third of the carapace; a short ridge, subja- 

 cent to the dorsal margin, extends from the dorsal 

 tubercle terminating behind and above a shallow 

 subcentral pit ; subcentral pit outlined above by a 

 short sharp ridge parallel to the dorsal margin. 



Dimensions : Holotype : length 0.57 mm ; height 

 0.31 mm; biconvexity 0.18 mm. 



Occurrence : Peedee only, localities A, C, and E. 

 U.S.N.M. 128908, 128909, 128910. 



Remarks : The shape, wide-spacing of the pos- 

 terior tubercles and arrangement of the ridges 

 distinguishes this species from C. sivaini and C. 

 andrewsi, n. sp.'s. 



Cytherelloidea andrewsi Brown, n. sp. 



Plate 1, Figures 24, 27, 28 



Carapace small, subovate in lateral view; dor- 

 sal margin gently arched ; ventral margin straight, 

 slightly concave medially ; anterior margin broad- 

 ly and evenly rounded ; posterior margin more 

 narrowly rounded than anterior. Right valve 

 larger than left, overlap greatest along dorsum. 



Marginal rim commencing at antero-dorsal 

 junction follows anterior, ventral and posterior 

 margins, posterad of dorsum, medially, the ridge 

 curves inward and around a deep subcentral pit, 

 becomes slightly sinuous beneath the subcentral 

 pit, and terminates just short of the marginal rim 

 at the postero-dorsal junction; a second promi- 

 nent ridge, separated from the subcentral pit by 

 a prominent elongate depression, rises in anterior 

 third, parallels the ventral margin and curves up- 

 ward posteriorly to terminate just short of the 

 posterior rim medially. The subcentral pit con- 

 tains a weak ridge giving the pit the appearance 

 of being subequally divided. 



Dimensions : Holotype : length 0.52 mm ; height 

 0.31 mm ; biconvexity 0.20 mm. 



Occurrence: Peedee only, localities A, C, and E. 

 U.S.N.M. 128911, 128912, 128913. 



Remarks : This species is named for Dr. T. G. 



9 



