Right valve larger, extending beyond left most strongly along dorsum and venter. Valves rather compressed, thickest in posterior half; female dimorphs slightly wedge-shaped in dorsal view, tapering toward anterior. Surface weakly and minutely punctate, a weak sulcus oc-curs mid-dorsally. In mature shells, mid-longitu-dinal section of valve forms a broad ridgelike swelling, in molts swelling is more ventral in po-sition. Right valve grooved along dorsum for reception of edge of left; a slight groove lies along ventral margin of right valve; terminally, grooves are barely perceptible.
Muscle scar not seen clearly owing to condition of preservation of the present specimens. Length of figured specimen PI. National Museum and found to be different in shape. The specimens identified by Schmidt , p. Among other described spe-cies from the Cretaceous, C. Texas Bull. Shaver, , Jour. Cytherella sp.
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Schmidt, , Jour. Cytherella cf. Survey Prof.
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Paper B, p. Shell subelliptical in side view, highest at or slightly posterior to midlength; dorsal margin gently convex ; ventral margin nearly straight terminal margins nearly equally rounded. Right valve extends strongly beyond left dorsally and ventrally, less strongly terminally; greatest ex-tension is mid-dorsal, where right valve is slightly umbonate.
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Valves moderately convex, thickest in posterior half. Surface smooth. Right valve with strongly incised shelf along dorsal and ventral margins for reception of edge of left; terminally, incisions are much shallower. Muscle scar a large group of radially arranged spots lying anterior to middle. Dimorphism exhibited posteriorly by relatively more tumid female shells, in contrast with the more compressed males ; females bear a low broad transverse median interior swelling and a corre-sponding shallow external depression.
Closely related, if not identical specimens were recorded by Schmidt , p. Page 3a. Cytherella beyrichoidcs Swain and Brown, n. Page 4a. Paleont, v. Butler and Jones, , Louisiana Dept. Howe and Laurencich, , Introd. Study Cretaceous Ostracoda, p. The species was described in detail by Alexan-der and by Butler and Jones and the present specimens fit the earlier descriptions. The diag-nostic features are the ovate outline, strong right valve overlap, and posterior marginal blunt pro-jection of right valve. Length of figured specimen 0. The present occurrence in Eagle Ford equivalents extends the species considerably farther down in the Creta-ceou than heretofore recorded: Genus Cytherelloidea Alexander, Cytherelloidea ontovariosa Swain and Brown, n.
Plate 1, Figures 4a-e Shell subquadrate in lateral view; dorsal mar-gin nearly straight with posterocardinal angle less obtuse than anterocardinal angle; ventral margin slightly concave medially, passing more abruptly into posterior than into anterior margin terminal margins broadly rounded, posterior trun-cated.
Right valve larger than left, extending beyond the other most noticeably along ventral and midportion of dorsal margins. Valves com-pressed, thickest posteriorly. Anterior margin of each valve bears a high marginal rim, broad at the base, narrow-crested, terminating a little posterior to anterior marginal bend, continuing as a much lower ridge along venter to posterior end ; a discontinuous, irregular narrow ridge rises near posterocardinal angle and trends obliquely forward to anteroventral region; posterior end bears strongly elevated rim that overhangs outer valve margin ; ventral and dorsal to midheight, on inner flank of posterior ridge, are two node-like elevations both of which continue anteriorly as narrow ridges; the more dorsal of two ridges terminates near midlength, the other extends forward nearly to anterior marginal rim; dorsal to last mentioned ridge, yet ventral to mid-height is an additional short, weak, longitudinal ridge.
A shallow excavation, or pit, occupies a slightly dorsomedian position. General surface in adult rather weakly pitted. Immature molts are much more coarsely pitted in comparison to their size than adult shells; the surface ridges are narrower and lower; the two posterior nodes are weakly developed and the ven-tromedian surface of the valve, particularly in posterior portion, is swollen.
In smallest molts the medium excavation is represented by a shallow sulcus in dorsal half of valve pi. Length of holotype PI. Study Cre-taceous Ostracoda, p. Shell triangular-ovate, highest medially, height a little more than half length; dorsal margin strongly and more or less evenly convex; ventral margin gently convex in left valve, sinuous in right; anterior margin narrowly rounded, ex-tended medially, curved below, truncated above; posterior margin produced below as rather strong subacute beak. Left valve larger than right, ex-tending strongly beyond right along dorsum, an-terior and posterior slopes and midventer, little or no extension terminally.
The hinge consists of a groove in the hinge face of the left valve into which fits edge of right valve. Along dorsal slopes, crenulations that are characteristic of Bairdoppilata Coryell, Sample and Jennings are lacking. Inner lamellae of moder-ate width, with line of concrescence and inner margin slightly separated terminally. Other in-ternal features obscured by recrystallization and by matrix. Apparently this is a mat-ter of preservation, because the more weakly pitted shells mostly appear to be abraded or re-crystallized.
The species was described as rare in the upper part of the Denton and lower part of the Weno Formations, middle Washita Group of northeastern Texas. Plate 1, Figure 6 Shell subtriangular in side view, highest medi-ally ; dorsal margin strongly convex, subacuminate medially; ventral margin gently convex, some-what sinuous ; anterior margin narrowly rounded, extended below; posterior margin acuminate, strongly extended below. Left valve moderately convex. Length of figured left valve 0. The strongly convex dorsum and general outline are suggestive of Bairdoppilata acuticauda Veen , p.
Alexander, , Univ. Paracypris goodlayidensis Howe and Laurencich, , Introd.
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Shell elongate-sublanceolate in side view, high-est about three-eighths from anterior end ; dorsal margin moderately convex, truncated posterior to position of greatest height and with broadly ob-tuse posterior cardinal angle in some specimens, evenly rounded in others; ventral margin long and nearly straight, slightly concave in midpor-tion; anterior margin rounded with greatest ex-tension ventral to midheight; posterior margin acuminate ventral to midheight.
Left valve larger than right, overlapping and extending beyond the other most conspicuously along venter, less so along dorsum and dorsal slopes. Hinge edge of right valve smooth and simple, apparently overlapped slightly by edge of left. Inner lamellae very broad terminally, although partly concealed in single separated right valve at hand. Muscle scar not observed PL 1, Fig. Length of a figured specimen PI. Shell elongate-acuminate in side view, highest three-eighths to one-half of distance from anterior end ; dorsal margin moderately convex, truncated anterior to greatest height ; ventral margin gently concave ; anterior margin rounded, slightly ex-tended below ; posterior margin very strongly ex-tended and acuminately pointed ventral to mid-height.
Left valve larger than right overlapping and extending beyond the other along ventral and anterodorsal margins. Valves compressed, thick-est medially to anteromedially. Internal features not observed. Sun Oil Company No. Paracypris sp. Plate 1, Figure 9a, b Shell elongate, subacuminate in side view, highest about three-sevenths from anterior end; dorsal margin moderately and nearly uniformly convex; ventral margin nearly straight, very slightly concave medially ; anterior margin rounded, with greatest extension at or slightly ventral to midheight; posterior margin narrowly rounded, subacuminate, strongly extended below midheight.
Left valve larger than right, extending most noticeably beyond the other along ventral and anterodorsal margins.
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Inter-nal features not observed. The generally larger size, more extended and acuminate posterior end and trun-cated dorsal margin of P. Shell elongate, sublanceolate in side view, highest medially; dorsal margin moderately con-vex, with truncated anterior slope ; ventral margin nearly straight, slightly sinuous; anterior margin nearly uniformly rounded; posterior margin bluntly acuminate, strongly extended below. Valves unequal, the left overlapping and extend-ing beyond right except anteroventrally, where overreach is slight or lacking; anterodorsally, a small flaplike extension of left valve results in slightly greater overlap than elsewhere, a similar but weaker flap occurs on anterodorsal slope.
Valves compressed, greatest convexity median. Internal features could not be observed clearly in the type specimens. These are here referred, tentatively, to P. Paracypris cf. Paracypris aff. Swain, , Maryland Dept. Shell elongate, subreniform-lanceolate in side view, highest medially; dorsal margin moderately convex, sloping more steeply behind than in front of position of greatest height; ventral margin concave medially; anterior margin uniformly rounded ; posterior margin acuminate and strongly extended below. Left valve larger than right over-lapping and overreaching right around most if not all of periphery.
Valves compressed, greatest con-vexity median. Length of figured specimen PL 4, Fig. The present specimens are somewhat less acuminate posteriorly than typ-ical P. The shape and overlap are closely similar to those of P.
The form identified as P. Cypridea cf. Cal-ahan, , Shreveport Geol. Guidebook 14th Annual Field Trip, p. Cypridea kleinbergi Galeeva, , op.
Left valve larger than right, overlapping and extending beyond right terminally and ven-trally; dorsally, right valve extends slightly be-yond edge of left. Valves compressed, most convex posteromedially. Anteroventral submarginal portion of each valve bears a prominent hood, projecting beak, and postjacent furrow which terminates in margi-nal notch.