118 FORAMINIFERA 



base of the inner margin, or consisting of a row of rounded 

 pores. 



Cretaceous to Recent. 



Genus BIGENERINA d'Orbigny, 1826 



Plate 11, fibres 10-13; plate 13, figure 9 



Genotype, by designation, Bigenerina nodosaria d'Orbigny 



Bigenerina d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 261. 

 Gemmulina d'Orbigny, 1. c, p. 262 (genotype, Bigener-ina (Gemmulma) 

 digitata d'Orbigny^. 



Test free, the early chambers biserial, later ones uniserial in 

 a rectilinear series, not labyrinthic; wall usually thick, 

 arenaceous, usually coarse but often smoothly finished ; aperture 

 in the young biserial stage at the base of the inner margin of 

 the chamber, in the adult uniserial stage terminal, rounded or 

 oval, simple. 



Carboniferous to Recent. 



In the microspheric form the earliest chambers show more or 

 less of the planispiral coiling, but this is not usually found in the 

 megalospheric form. 



Genus VULVULINA d'Orbigny, 1826 



Plate 11, figures 14-16; plate 13, figure 13 



Genotype, by designation, Vulvulina capreolus d'Orbigny 



Vulvulina d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 264. 



Nautilus (part) Batsch, Conch. Seesandes, 1791, no. 13, pi. 4, figs. 13 a-d. 



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



Schizo'phora Reuss, Sitz. bohm. Ges. Wiss., vol. 2, 1861, p. 13 (genoholo- 



type, S. neiigehoreni Reuss). 

 Grammostomum (part) Parker and Jones (not Ehrenberg), Ann. Mag. 



Nat. Hist., ser. 3, vol. 11, 1863, p. 93. 

 VeniUna GtJMBEL, Abhandl. Kon. bay. Akad. Wiss., CI. II, vol. 10, 1868, 



p. 647 (genotype, by designation, V. nurivmuUna Gumbel). 

 Textilaria (part) GiJMBEL (not Defrance), 1. c, p. 647. 

 Trigenerina Schubert, Verhandl. k. k. Geol. Reichs., 1902, p. 84 



(genotype, Vulvulina capreolus d'Orbigny). 



Test free, much compressed throughout, early stages biserial, 

 or slightly coiled in the microspheric form, later chambers uni- 

 serial, simple ; wall finely arenaceous with a large proportion of 

 cement; aperture elongate, elliptical, simple, terminal. 



Eocene to Recent. 



