Cytherella tuberculifera Alexander 



Plate 1, Figures 3a, b 



Cytherella tuberculifera Alexander, 1929, Univ. 



Texas Bull. 2907, p. 52, pi. 2, fig. 2; 1934, Jour. 



Paleont, v. 8, p. 212. 



Butler and Jones, 1957, Louisiana Dept. Cons. 

 Geol. Bull. 32, p. 9, pi. 6, fig. 7. 



Howe and Laurencich, 1958, Introd. Study 

 Cretaceous Ostracoda, p. 257, text fig. 



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 0.70 mm, height 

 0.42 mm, convexity 0.32 mm. 



Occurrence. — The species is rare in strata as- 

 signed an Eagle Ford (upper member of Atkinson) 

 age by P. L. and E. Applin (written communica- 

 tion) in the Humble Oil and Refining Company's 

 Tindel No. 1 well, Jackson County, Florida, core 

 sample 2,881-2,891 feet. The species has been re- 

 corded previously from the Paleocene Midway and 

 Upper Cretaceous Navarro Group, of North Texas, 

 the Upper Cretaceous of North Carolina, and in 

 beds assigned a Late Cretaceous Saratoga age 

 from Prothro Salt Dome, Bienville Parish, Louis- 

 iana (Butler and Jones, 1957, p. 9). The present 

 occurrence in Eagle Ford equivalents extends the 

 species considerably farther down in the Creta- 

 ceou than heretofore recorded: 



Genus Cytherelloidea Alexander, 1929 



Cytherelloidea ontovariosa Swain and Brown, 



n. sp. 



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. 1, fig. 4a). 



Length of holotype (PI. 1, Fig. 4a) 0.66 mm, 

 height 0.36 mm, thickness 0.22 mm. 



Relationships. — The pattern <ef surface ridges 

 in this species serves to distinguish it from other 

 described members of the genus. C. reticulata 

 Alexander (1929, p. 57) from the Weno Clay and 

 upper part of the Denton Clay of the middle 

 Washita Group of Texas is similar in general dis- 

 tribution of surface ridges, but lacks the oblique 

 mid-dorsal ridge. 



Occurrence. — Lower member of Atkinson For- 

 mation in the following wells: (1) Humble Oil and 

 Refining Company, No. 1 Bennett and Langdale 

 well, Echols County, Georgia, cores 3,690-3,700 

 and 3,700-3,710 feet; (2) Union Producing Com- 

 pany, No. 1 Kirkland well, Houston County, Ala- 

 bama, cuttings 3,280-3,290 feet; (3) Sun Oil Com- 

 pany, No. 1 Johnson well, Columbia County, 

 Florida, core 2,955-2,965 feet. 



Suborder Podocopina Sars, 1866 



Superfamily Bairdiacea Sars, 1888 



Family Bairdiidae Sars, 1888 



Genus Bairdia McCoy, 1844 



Bairdia comanchensis Alexander 



Plate 1, Figures 5a-c 



Bairdia comanchensis Alexander, 1929, Univ. 

 Texas Bull. 2907, p. 63, pi. 2, fig. 15, pi. 3, fig. 4. 



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