NO. II FORAMINIFERA OF VENEZUELA GRAVELL I7 



Genus HETEROSTEGINA d'Orbigny 



HETEROSTEGINA sp. cf. H. ANTILLEA Cushman 



Plate I, fig. 12 



Heterostegim antillca Cushman (14, p. 49, pi. 2, fig. i ; pi. 5, figs. 1-2). 

 Hcterostegina anfillea Cushman (16, p. 131, pi. 20, figs. 13, 14). 



Test medium-sized, thin ; diameter up to about 8.0 mm ; thickness 

 through umbo up to about 0.7 mm, generally about 0.5 mm. The 

 umbonate area low and gently curved; excentrically located, about 

 1.5 mm from the margin of the test, surrounded by a wide, thin 

 flange ; thickness of flange at junction of umbonate area about 0.35 

 mm, decreasing gradually to about 0.17 mm at the periphery of the 

 test. The test is composed of about two and one half whorls, which 

 rapidly increase in width. 



Localities and geologic horizons. — Hcterostegina sp. cf. H. antillea 

 and Camerina sp. a compose a large part of the material from localities 

 482, 497, 1 147, 1 157, 1166, and 1222. A few sections of Hetero- 

 stegina which may be H. sp. cf. H. antillea occur in thin sections of 

 material from localities 496, 1210. 1221. All of the above listed 

 localities are in the Nummulitic Limestone series, upper to lower 

 Oligocene. 



In thin sections Hcterostegina sp. cf. //. antillca closely resembles 

 Hcterostegina antillea Cushman. No positive identification could be 

 made, because the surface ornamentation could not be studied, owing 

 to the impracticability of separating the fragile specimens from their 

 indurated matrix. 



HETEROSTEGINA PANAMENSIS Gravell, n. sp. 



Plate I, figs. 10, II 



Heterostegim sp. Vaughan (47, p. 789). 



Test of the megalospheric form small ; diameter up to about 3.0 

 mm ; thickness up to about 0.75 mm ; test composed of a rounded 

 thickened area occupying about one half of the diameter, surrounded 

 by a thin flange, which increases in breadth, giving the thickened 

 area an excentric position. In the center of this thickened area is a 

 small umbo of light-colored shell material. Periphery of the test 

 broadly rounded ; central portion ornamented by irregular, radial, 

 slightly raised costae, which meet the chamberlets near the base of the 

 thickened area. Test composed of about three and one half whorls, 

 which gradually increase in breadth. 



