294 FORAMINIFERA 



Genus EHRENBERGINA Reuss, 1850 



Plate 43, figures 21-23; plate 46, figure 6 

 Genoholotype, Ehrevhergina serrata Reuss 

 Ehrenbergina Reuss, Denkschr. k. Akad. Wiss. Wien, vol. 1, 1850, p. 377. 

 Cassidulina (part) d'Orbigny, 1839. 



Test with the young, at least in the microspheric form, 

 compressed, planispiral, in the adult with the test compressed at 

 right angles to that of the early coiling and becoming uncoiled, 

 developing a dorsal side which is flattened or slightly convex 

 and a ventral which is thickest near the median line; aperture 

 elongate, on the ventral side near the periphery. 



Eocene to Recent. 



See Cushman, Foraminifera of the Genus Ehrenbergina and 

 its Species (Proc. U. S. Nat. Mus., vol. 70, Art. 16, 1927, pp. 1-8, 

 pis. 1,2). 



This family is very closely related to the Rotaliidae, through 

 such genera as Valvulineria, the test in Ceratobulimina being 

 umbilicate with a change in the aperture clearly foreshadowing 

 the conditions typical of Cassidulina. The uncoiled forms follow 

 in their natural sequence. Ehrenbergina becoming compressed 

 in a plane at right angles to the early coiling and with the adult 

 chamber uncoiled, gives a new structural modification. On the 

 basis of the biserial form, several of these genera have often been 

 grouped with the Textulariidae. The Cassidulinidae are cal- 

 careous, perforate, and have their close relationships to the 

 Rotaliidae very clearly marked. 



FAMILY 38. CHILOSTOMELLIDAE 



Test in the early stages of the simpler genera typically 

 trochoid, the chambers all visible from the dorsal side, only those 

 of the last-formed chamber visible from the ventral side, the 

 chambers in later development variously arranged, typically 

 planispiral and involute so that the early stages are completely 

 covered ; wall calcareous, perforate ; aperture typically on the 

 ventral side, at least in the early stages, in the planispiral forms 

 becoming median. 



