NEW TERTIARY FORAMINIFERA VAUGHAN AND COLE 489 



Remarks. — This species is closely related to O. marianneTisis 

 Vauglian (1928, p. 158) from the upper Eocene Ocala limestone of 

 Florida, from which it is distinguished by its thicker, more robust 

 form, its larger number of chambers, and its more evolute coiling. 

 There arc 11 or 12 chambers in the final coil of marlannensis, while 

 slightly smaller specimens of tuherculaia have 16 or 17. The 

 granulations are coarser and the intercostal areas narrower in tj^pical 

 specimens of tuherculata. 



Genus OPERCULINOIDES Hanzawa 



OpercuUnoidcs Hanzawa, Tohoku Imp. Univ. Sci. Rept., ser. 2 (Geol.), vol. 18, 

 no. 1, p. IS, 1935. 



Genoholotype. — NutmnuUtes willcoxi Heilprin. 



Hanzawa says : "On examining the foregoing listed specimens of 

 OjjercuUna [4 species] from America, I found that they all differ 

 from either Operculina eoiiiflanata (senso latu) or O 'perculinella 

 venosa by being involute in the adult stage." A re-examination of 

 O perculinella venosa shows that Hanzawa is correct in generically 

 separating the American Tertiary species that have been referred to 

 Operculinella Yabe from that genus and in proposing a new generic 

 name for those typified by Nuvvmulites willcoxi Heilprin. It seems 

 better to refer such species as those represented by Nwininulites flori- 

 densis Heilprin to another genus, AssiUna, as Cushman has done; 

 but it must be recognized that the members of the group need 

 additional and more critical study. 



OPERCULINOIDES ADVENUS, new species 



Plate 35, Figures 5-7 



Test of medium size, involute, much compressed, the sides nearly 

 parallel, with a very bluntly rounded periphery. Diameter from 

 outer edge of aperture through center ranges from 1.9 to 3.6 mm; 

 diameter at right angles to line through aperture ranges from 1.8 

 to 3.4 mm; thickness through center ranges from 0.3 to 0.5 mm. 

 The surface is smooth, not ornamented, in well-preserved speci- 

 mens; in weathered specimens the sutures appear as slightly raised 

 lines, radiating with gentle curvature from the center to the periph- 

 ery of the test. 



A median section of a specimen 1.9 mm in diameter has 4 com- 

 ])lete coils, with 22 chambers in the final coil; the specimen shown 

 in plate 35, figure 6, is 3 m.m in diameter and has 28 chambers in 

 ihe last coil. The variation in the number of chambers in the final 

 volution is from 20 to 28. The initial chamber is circular, about 88ju. 

 in diameter. The chambers increase slowly but regularly in height. 



