The Cainozoic strata in all parts of the world are very rich in Foraminifera, and the genera, and even many species are similar to those now found living. Certain types, however, had a restricted range, and are therefore useful as indicators of age. Such are the Nummulites and the _Orbitoides_ of the Eocene and the Oligocene of Europe, India and the West Indies; and the _Lepidocyclinae_ of the Miocene of Europe, India, Japan and Australia (Fig. 64). The genus _Lepidocyclina_ is typically represented in the Batesford beds near Geelong, Victoria by _L. tournoueri_, a fossil of the Burdigalian stage (Middle Miocene) in Europe, as well as by _L. marginata_. A limestone with large, well-preserved tests of the same genus, and belonging to a slightly lower horizon in the Miocene has lately been discovered in Papua. [Illustration: =Fig. 65.--CAINOZOIC FORAMINIFERA.= A--Miliolina vulgaris, d'Orb. sp. Oligocene-Recent. Vict. and S.A. B--Textularia gibbosa, d'Orb. Oligocene and Miocene. Vict. & S.A. C--Nodosaria affinis, d'Orb. Oligocene. Victoria. D--Polymorphina elegantissima. P. and J. Oligocene-Recent. Vict. and S.A. E--Truncatulina ungeriana, d'Orb. sp. Oligocene-Recent. Vict. & S.A. F--Amphistegina vulgaris, d'Orb. Oligocene-L. Pliocene. Vict. & S.A. ] Some of the commoner Foraminifera found in the Cainozoic beds of Southern Australia are--_Miliolina vulgaris_, _Textularia gibbosa_, _Nodosaria affinis_, _Polymorphina elegantissima_, _Truncatulina ungeriana_ and _Amphistegina lessonii_ (Fig. 65). The first-named has a chalky or porcellanous shell; the second a sandy test; the third and fourth glassy or hyaline shells with excessively fine tubules; the fifth a glassy shell with numerous surface punctations due to coarser tubules than usual in the shell-walls; whilst the last-named has a smooth, lenticular shell, also hyaline, and occurring in such abundance as often to constitute a foraminiferal rock in itself. =Pleistocene Foraminifera.--= The estuarine deposits of Pleistocene age in southern Australia often contain innumerable shells of _Miliolina_, _Rotalia_ and _Polystomella_. One thin seam of sandy clay struck by the bores in the Victorian Mallee consists almost entirely of the shells of the shallow-water and estuarine species, _Rotalia beccarii_. * * * * * =Radiolaria: Their Structure.--= The organisms belonging to the order _RADIOLARIA_ are microscopic, and they are all of marine habitat. The body of a radiolarian consists of a central mass of protoplasm enclosed in a membranous capsule, and contains the nuclei, vacuoles, granules and fat globules; whilst outside is a jelly-like portion which throws off pseudopodia or thin radiating threads. The skeleton of Radiolaria is either chitinous or composed of clear, glassy silica, and is often of exquisitely ornamental and regular form. =Habitat.--=