46 FORAMINIFERA 



Orhitolites, Opertorbitolites, Alveolinella, Flosculina, Borelis, 

 Operculina, Heterostegina, Camerina, Asterigerina, Amphiste- 

 gina, Lepidocyclina, Discocyclina, and others develop large 

 species. The higher groups of the Rotaliidae and derived families 

 appear. While many of these had specialized species the general 

 character of the fauna has persisted and many of the genera are 

 now found living in the shallow waters of the Indo-Pacif ic. As 

 the Tertiary progresses, species are replaced by more modern 

 ones, and gradually the fauna comes to that of the present 

 oceans. Outside of the Allogromiidae which naturally would 

 not be found in the fossil state, none of the families except the 

 Neusinidae and Kerammosphaeridae are wholly represented by 

 recent species. These two are very specialized families with very 

 few genera and species, and very limited in their distribution at 

 the present time. The accompanying chart shows the distribu- 

 tion of the families in geologic time, the dotted portion the 

 probable range where not yet definitely known. 



