STUDIES IN FOBAMINIFERA 



185 



finely perforate, surface spinose; primary aperture a 

 small high arch, interiomarginal and umbilical in po- 

 sition, secondary apertures tiny along the sutures on 

 the spiral side. Specimens range from 0.15 to 0.35 

 mm. in greatest diameter. 



Rem.irks: This species was originally described 

 from the Danian of Jutland, Denmark, and was placed 

 in the genus Olobigerina d'Orbigny, as the small sup- 

 plementary apertures of the spiral side were not ob- 

 served. These openings have since been noted on type 

 Danian specimens by Troelsen (1957), and are here 

 shown in specimens from the Danian of Sweden, as 

 well as from those of the Gulf and Atlantic Coast 

 Paleocene. In his original description Bronnimann 

 (1953, p. 339) stated that the type Danian contains 

 "a small number of characteristic Olobigerina and 

 Olohorotalia species, which, with the exception of 

 Olobigerina daubjergensis n. sp., are known from the 

 Paleocene of Texas . . " This characteristic species 

 is also quite abundant in both the Kincaid and Wills 

 Point formations of the Midway group in Texas, 

 probably having been overlooked in the past due to 

 its small size. It occms also in the Pine Barren and 

 McBryde members of the Clayton formation of Ala- 

 bama, and in the Brightseat formation of Maryland. 



Types and occurrence: The holotype was de- 

 scribed from the Danian at Daubjerg, quarry south- 

 west of Stavnsbjerg Farm, Denmark. Originally 

 stated to be deposited in the Cushman Collection, 

 U. S. National Museum, Washington, D. C, but 

 not as yet deposited therein. 



Figured hypotype (USNM P5709) from the upper 

 Danian, zone of Tylocidaris veonlifera Schliiter, from 

 calcarinite at Ostra Torp, Sweden. Collected by J. 

 G. Carlsson. 



Figm-ed hypotype (USNM P5710) from the Kincaid 

 formation in a small stream bank on the east side of 

 the road, 3 miles northwest of Elgin, on the secondary 

 road leading to Lund, and lying on the Bastrop-Travis 

 Coimty line, about 0.5 mile north of its junction with 

 the Austin-Elgin highway, Texas. Collected by A. R. 

 Loeblich, Jr. 



Figured hypotype (USNM P5711) from the Wills 

 Point formation, 200 feet east of the bridge over 

 Tehuacana Creek in bank of creek, 4 miles north of 

 Mexia on the Mexia-Wortham road. Limestone 

 County, Texas. Collected by A. R. Loeblich, Jr. 



Figured hypotype fUSNM P5712) from the Mexia 

 clay member of the Wills Point formation, in abandoned 

 pit of Mexia Brick Works at Mexia, Limestone County, 

 Texas. Collected by A. R. Loeblich, Jr. 



Figured hypotype (USNM P5713) from the Pine 

 Barren member of the Clayton formation, blue-black 

 micaceous clay in road cut opposite country store, 

 0.8 mile west of Alabama River Bridge on Alabama 

 Highway 28, Wilcox County, Alabama. Collected 

 by A. R. Loeblich, Jr. 



Figured hypotype (USNM P5714) from the Mc- 

 Bryde limestone member of the Clayton formation, 

 in bed of Rock Creek, 0.8 mile south of jimction of 



Alabama Highways 28 and 10, on Highway 10, Wilcox 

 County, Alabama. Collected by A. R. Loeblich, Jr. 



Figured hypotypes (USNM P5715a,b) from the 

 type locality of the Brightseat formation, 1 mile west- 

 southwest of Brightseat and 0.2 mile south of Sheriff 

 Road, Prince Georges County, Maryland. Collected 

 by A. R. Loeblich, Jr., and Richard A. Page. 



Family Globorotaliidae Cushman, 1927 



Genus Globorotalia Cushman, 1927 



Cloborotalia acuta Toulmin 



Plates 47, Figures 5a-c; 55, Figures 4a-5c; 58, Figures 5a-c 



Globorotalia wilcoxensis Cushman and Ponton var. acuta Toul- 

 min, Journ. Paleontol., vol. 15, p. 608, pi. 82, figs. 6-8, 

 1948. — Shifflet, Maryland Dep. Geol., Mines and Water 

 Resources Bull. 3, p. 73, pi. 4, figs. 23a-e, 1948. 



Globorotalia (Truncorotalia) lacerti Cushman and Renz, Hofkbb, 

 Rep. McLean Foram. Lab., No. 2, p. 14, pi. 1, 1955. 



Test free, planoconvex, umbilicoconvex, periphery 

 keeled, umbilical shoulder sharply angled and strongly 

 spinose, imibilicus relatively wide and open; chambers 

 angular conical in shape, increasing gradually in size 

 and angularity, all the 2 to 2^ whorls visible on the 

 flat spiral side, only the 4 to 6 chambers of the final 

 whorl visible on the angularly convex umbilical side; 

 sutures distinct and thickened, but flush with the sur- 

 face, oblique and directed sharply backwards on the 

 spiral side, radial and depressed on the umbilical side; 

 wall calcareous, distinctly and coarsely perforate, sur- 

 face spinose, with a somewhat sugary appearance 

 especially in the earlier chambers, peripheral margin 

 with a spinose keel and highly ornamented, very sharply 

 angled or even keeled umbilical shoulder; aperture 

 interiomarginal, extraumbilical-umbilical, with a dis- 

 tmctly triangular toothlike lip, earlier apertiu-es remain- 

 ing open into the wide umbUicus. 



Hypotypes range in diameter from 0.20 to 0.55 mm. 

 in diameter and in thickness from 0.13 to 0.28 mm. 



Rem.^rks: This species has in the past been variously 

 referred to as a variety (or subspecies) of Globorotalia 

 wilcoxensis (by Toulmin, 1941, p. 608) or as a variety 

 of 0. velascoensis Cby Grimsdale, 1951, p. 471). Bolli 

 (1957) regards it as synonymous with 0. velascoensis, as 

 he stated that a gradation occurs between these forms 

 in the Velasco shale of Mexico. Although both forms 

 do occur in the Velasco, we regard the two species as 

 distinct, for in more northern regions only specimens 

 lilve the typical 0. acuta have been observed. This is 

 true of the Salt Mountain limestone of Alabama where 

 0. acuta was first described, the Aquia formation of 

 Virginia, and the Vincentown formation of New 

 Jersey; in each region O. acuta is abundantly repre- 

 sented, whereas there are no specimens similar to the 

 type of velascoensis. 



Oloborotalia acuta Toulmin differs from O. velascoensis 

 (Cushman) in being somewhat smaller and in having a 

 less pronounced peripheral keel than does 0. velascoensis. 

 Oloborotalia acuta has a more rapid increase in chamber 

 size, with the final chamber conmionly occupying % to 



