SMALLER FORAMINIFERA FROM ILLINOIS 



351 



2D; Salt Mountain limestone, Eocene, Ala- 

 bama. 



Test compressed, thickness about one- 

 half of diameter; periphery distinctly keeled 

 in early chambers, less so in final ones; 

 chambers 9 in last whorl; sutures almost 

 straight to slightly curved, raised, distinctly 

 limbate, subtangent to, but not meeting 

 umbo in final two or three chambers; di- 

 ameter, 2.0 mm.; thickness, 1.1 mm. 



This form seems identical with R. mag- 

 nificus described by Toulmin from Alabama, 

 except that the sutures of the Illinois spec- 

 imen are somewhat less curved. 



RoBULUS MiDWAYENSis (Plummer) 

 Plate 55, figures 22, 23 



Cristellaria midwayensis Plummer, 1927, Texas 

 Univ. Bull. 2644, p. 95, pi. 13, figs. 5a-c; Mid- 

 way group. Paleocene, Texas. 



Lenticulina midwayana Israelsky, 1939, Proc. 

 Sixth Pacific Sci. Cong., p. 573, pi. 2, figs. 7, 8; 

 Marysville formation (Capay stage). Eocene, 

 California. 



Rohulus midwayensis Cushman, 1940, Cushman 

 Lab. Foram. Research Contr., vol. 16, p. 54, 

 pi. 9, fig. 12; Midway group, Paleocene, Ala- 

 bama. — Toulmin, 1941, Jour. Paleontology, 

 vol. 15, p. 579, pi. 78, fig. 23, text fig. 2G; 

 Salt Mountain limestone, Eocene, Alabama. 



Test large, only slightly compressed, di- 

 ameter and thickness about equal; chambers 

 9 in last whorl; slightly curved, almost equal 

 in size, increasing very gradually to final 

 chamber; sutures prominent, limbate, taper- 

 ing, with greatest curvature near peripheral 

 margin; diameter and thickness, about 1.2 

 mm. 



The Illinois specimen is nodose and thus 

 resembles the Texas form but Salt Mountain 

 specimens have a smooth umbo. This 

 species is a good Midway marker in Texas. 



Genus Vaginulina d'Orbigny 



Vaginulina gracilis Plummer 



Plate 55, figures 5, 6 



Vagulina gracilis Plummer, 1927, Texas Univ. 

 Bull. 2644, p. Ill, pi. 6, figs. 5a-b; Midway 

 group, Paleocene, Texas. — Cushman, 1940, 

 Cushman Lab. Foram. Research Contr., vol. 

 16, p. 61, pi. 9, fig. 27; Midway group, Paleo- 

 cene, Alabama. 



Test tapering, slightly arcuate, com- 

 pressed; chambers short; sutures only 

 slightly oblique, marked by abrupt, narrow, 

 somewhat nodose and discontinuous ridges; 



diameter, average, 0.3 mm; height, 5 cham- 

 bers, 0.50 mm. 



This species is common in the lower Mid- 

 way of Alabama and Texas, where it is suc- 

 ceeded in the upper Midway by V. rohusta 

 Plummer. 



Vaginulina robusta Plummer 

 Plate 55, figures 16, 17 



Vaginulina rohusta Plummer, 1927, Texas Univ. 

 Bull. 2644, p. 112, pi. 6, figs. 4a-b, pi. 13, fig. 

 3; Midway group, Paleocene, Texas. — Cush- 

 man, 1940, Cushman Lab. Foram. Research 

 Contr., vol. 16, p. 61, pi. 10, figs. 1-4; Midway 

 group, Paleocene, Alabama. 



Test, large, robust, slightly compressed; 

 straight; chambers smooth, short but quite 

 broad; sutures transverse to slightly oblique, 

 prominent, somewhat nodose; nodes discon- 

 tinuous along more convex edges (in double 

 row on broader edge, see figs. 16, 17); 

 average diameter, 0.8 mm; height, 5 cham- 

 bers, 1.3 mm. 



This species is characteristic of the upper 

 Midway in Texas and Alabama. It is 

 straighter and more robust than V. gracilis. 



Family Heterohelicidae Cushman 



Genus Rectogumbelina Cushman 



Rectogumbelina alabamensis Cushman 



Plate 55, figures 3, 4 



Rectogumbelina alabamensis Cushman, 1940, 

 Cushman Lab. Foram. Research Contr., vol. 

 16, p. 65, pi. 11, fig. 16; Midway group, Paleo- 

 cene, Alabama. 



Test very small, slightly arcuate, slender, 

 tapering; early chambers biserial, later ones 

 uniserial, biserial chambers less inflated; 

 early sutures slightly and less depressed 

 than later ones; diameter 0.065-0.145 mm.; 

 length, 0.37. 



Although slightly larger than the form de- 

 scribed by Cushman from Alabama, the Illi- 

 nois specimen seems to conform in all other 

 respects. Common in the upper Midway of 

 Alabama. 



Genus Siphogeneroides Cushman 



Siphogeneroides? eleganta (Plummer) 



Plate 54, figure 14 



Siphogenerina eleganta Plummer, 1927, Texas 

 Univ. Bull. 2644, p. 126, pi. 8, figs, la-c; Mid- 

 way group, Paleocene, Texas. — Cushman, 1940, 

 Cushman Lab. Foram. Research Contr., vol. 

 16, p. 66, pi. 11, fig. 17; Midway group, Paleo- 

 cene, Alabama. 



