272 FORAMINIFERA 



Genus GYROIDINA d'Orbigny, 1826 

 Plate 39, figure 13; plate 41, figure 7 



Genotype, by designation, Gyroidina orbicularis d'Orbigny 

 Gyroidina d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 278. 

 Rotalina (part) of authors. 



Test trochoid, usually with the ventral side convex, the 

 umbilicus small and deep ; chambers in the central region usually 

 higher than the peripheral ones and separated by a depressed 

 channel ; wall calcareous, finely perforate ; aperture, a low 

 arched opening on the ventral side toward the umbilical area. 



Lower Cretaceous to Recent. 



Genus ROTALIATINA Cushman, 1925 



Plate 39, figure 14; plate 41, figure 8 



Genoholotype, Rntaliativa mexicana Cushman 

 Rotaliatina Cushman, Contr. Cushman Lab. Foram. Res., vol. 1, 1925, 



p. 4. 

 Rotalina (part) of authors (not d'Orbigny). 



Test free, trochoid, close coiled, composed of about three 

 volutions, the last one composed of numerous chambers, all 

 visible from the dorsal side, only those of the last-formed coil 

 from the ventral side, ventrally umbilicate; wall calcareous, 

 finely perforate; aperture, an arched slit between the base of 

 the apertural face and the previous coil. 



Eocene. 



Subfamily 4. Rotaliinae 



Test trochoid, umbilical region typically closed, sometimes 

 with a definite conical plug of clear shell material; wall of the 

 test often double and a tubular canal system developed; aper- 

 ture ventral, along the margin of the chamber between the 

 periphery and the umbilical area. 



Genus EPONIDES Montfort, 1808 



Plate 40, figures 1, 2; plate 41, figure 9 

 Genoholotype, Nautilus re^^andus Fichtel and Moll 

 Eponides Montfort, Conch. Syst., vol. 1, 1808, p. 127. 

 Nautilus (part) of authors. 



