Genus Perissocytheridea Stephenson, 1936 



Perissocytheridea odomensis Swain and Brown, 

 n. sp. 



Plate 2, Figures 7, 8a, b 

 Text Figure 6b 



Shell subquadrate-acuminate in side view, 

 highest about one-fifth from anterior end ; dorsal 

 margin nearly straight, about three-fifths of shell 

 length, with well defined obtuse cardinal angles, 

 the posterior angle larger than the anterior ; ven- 

 tral margin gently convex; anterior margin 

 broadly rounded, slightly extended below; pos- 

 terior margin acuminately curved, strongly ex- 

 tended medially, concave above. Left valve a little 

 larger than right, overlapping and extending be- 

 yond right anteriorly and posterodorsally. Valves 

 strongly convex, greatest inflation posteromedian. 

 Terminal marginal zones compressed. 



Anterodorsal portion of each valve depressed as 

 a broad sulcus which extends only to midheight; 

 a large pointed node and dorsally-adjacent eye 

 tubercle define sulcus anteriorly; posterior to sul- 

 cus, surface strongly swollen as a node or lobe 

 which medially extends beyond dorsal margin ; 

 ventral portion of valve bears a series of three 

 nodes arranged as a subalate ridge; general sur- 

 face coarsely but weakly reticulate ; flattened ven- 

 tral surface bears about four low, narrow, longi- 

 tudinal ridges. 



Immature specimens are characterized by more 

 strongly reticulate and ridged surface ornamenta- 

 tion, but also have the dorsal nodes and sulcus 

 more weakly developed and have little or no de- 

 velopment of the ventral nodose ridge. 



Hinge of left valve consists of terminal very 

 elongate denticulate sockets that taper gradually 

 to extinction in direction of rather short inter- 

 terminal, weakly crenulate bar formed by edge of 

 valve. Muscle scar a small subvertical antero- 

 median row of four spots plus two additional, 

 considerably more anterior spots. Inner lamellae 

 of moderate width, vestibules developed termi- 

 nally ; radial canals rather few and widely spaced, 

 about ten anteriorly and five posteriorly, and with 

 additional canals ventrally. Normal canals few 

 and widely spaced. 



Length of holotype 0.77 mm, height 0.38 mm, 

 convexity excluding nodes 0.33 mm, convexity in- 

 cluding nodes 0.45 mm. 



Relationships. — The shape, sulcation and loba- 

 tion and internal structures of this species relate 

 it to Perissocytheridea. The pattern of surface 



nodes serves to distinguish this species from oth- 

 er described forms. This genus is characteristic 

 of lagoonal and estuarine conditions in which sa- 

 linity varies from brackish to hypersaline. 



Occurrence. — Lower Cretaceous, probably of 

 Washita (Albian) age, of the subsurface of north- 

 eastern North Carolina; Odom water well T-l, 

 Northampton County, 190-200 feet; Caledonia 

 Prison Farm water well T-2, Halifax County, 191- 

 196 feet, and T-4 well, 141-146 feet. 



Genus Schuleridea Swartz and Swain, 1946 

 Schuleridea washitaensis (Alexander) 



Plate 2, Figures 9a-e; Text Figure 6c 



Cytheridea washitaensis Alexander, 1929, Univ. 



Texas Bull. 2907, p. 71, pi. 4, figs. 12, 14. 



Calahan, 1939, Shreveport Geol. Soc. Guide- 

 book 14th Annual Field Trip, p. 45, pi. 5, 

 figs. 9, 10. 



Schuleridea washitaensis (Alexander). Howe and 



Laurencich, 1958, Introd. Study Cretaceous Os- 



tracoda, p. 494, text fig. 



Shell subtriangular-subpyriform in side view, 

 highest about two-fifths from anterior end ; dorsal 

 margin strongly convex, subangulate at position 

 of greatest height, sloping more steeply in front 

 of than behind position of greatest height ; ventral 

 margin nearly straight in right valve, gently con- 

 vex in left; anterior margin broadly curved, ex- 

 tended medially ; posterior margin narrowly 

 rounded, subacuminately extended below. Left 

 valve larger than right (although reversal has 

 been noticed) , extending beyond edge of right on 

 all except posterodorsal margin. Valves of moder- 

 ate tumidity, greatest convexity median in posi- 

 tion. Just anterior to apex of dorsum, right valve 

 bears a small oblique tubercle, presumably the eye 

 spot, and anteriorly-subjacent weak furrow. An- 

 terior margin, and to a lesser extent posterior 

 margin, of right valve bears a narrow thickened 

 lip. General surface of midportion of valves has 

 small, widely spaced pits. 



Hinge of left valve consists of elongate, termi- 

 nal, finely denticulate sockets and an intertermi- 

 nal, very weakly crenulate furrow, dorsal to which 

 is an accommodation groove ; hinge of right valve 

 has terminal, denticulate, elongate, elevated den- 

 tal areas and an interterminal crenulate bar. 

 Inner lamellae fairly broad terminally; line oi 

 concrescence and inner margin nearly coincide. 

 Musculature and pore canals not observed. 



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