FAMILY 45. ORBITOIDIDAE 337 



of Helicolepidina to Spiroclypeus, a modified Heterostegina, I 

 now regard as erroneous. 



Not all the nomenclature that follows can be regarded as 

 firmly established. No decision has been reached regarding the 

 disposition of Hymeyiocyclus Bronn, 1851-52. Perhaps this 

 name should be substituted for one of those here used. 



Subfamily Orbitoidinae 



Genus ORBITOIDES d'Orbigny, 1847 

 Plate 57, figure 4; plate 58, figures 1-6 

 Genolectotype, Orbitoides media (d'Archiac) 

 Orbitoides d'Orbigny, Quart. Jour. Geol. Soc. London, vol. 4, 1847, p. 11; 



Cours Element. Pal., vol. 2, 1850, p. 193, fig. 316. 

 Orbltclla H. Douville, C. R. Acad. Sci., voL 161, 1915, p. 666, figs. 5, 6; 

 Bull. Soc. Geol. France, 4th ser., vol. 20, 1921, p. 214. 



Test lenticular, more or less compressed, surface ornamented 

 with vermicular pillars or radiating costae. Embryonic cham- 

 bers enveloped in a thick shell, at first quadrilocular, later 

 becoming bilocular, by atrophy and fusion of three of the initial 

 chambers, and the production of a smaller embraced by a larger 

 chamber. Equatorial chambers with a curved outer wall and 

 inwardly converging lateral walls, radial diameter shorter than 

 the transverse. Communication between the chambers by a few 

 round lateral apertures. 



Upper Cretaceous. 



It is probable that Silvestrina Prever (Riv. ital. Paeontol., 

 vol. 10, 1904, p. 122, pi. 6, figs. 2, 3), 1904, is a synonym of 

 Orbitoides. 



Genus SIMPLORBITES de Gregorio, 1882 



Plate 58, figure 7 



Genoholotype, Numviulites papyracea Boubee, 1SS2 = Orbitolites gensacicus 



Leymerie, 1851 

 Simplorbites DB Gregorio, Fossili dei Dintorno di Pachino, 1882, p. 10, pi. 



6, figs. 21-28, 30. 

 Simplorbites H. DOUVILLE, C. R. Acad. Sci., vol. 161, 1915, p. 667, figs. 

 13-15; Bull. Soc. Geol. France, 4th ser., vol. 20, 1921, p. 217, figs. 19-21. 



Test inflated or compressed lenticular. Surface ornamented 

 with compressed vermicular or radiately elongate pillars similar 



