Lower Miocene, United states: Nebraska.—In the territory of Nebraska, on the Upper Missouri, near the Platte River, lat. 42° N., a tertiary formation occurs, consisting of white limestone, marls, and siliceous clay, described by Dr. D. Dale Owen,[8] in which many bones of extinct quadrupeds, and of chelonians of land or fresh-water forms, are met with. Among these, Dr. Leidy describes a gigantic quadruped, called by him _Titanotherium,_ nearly allied to the _Palæotherium,_ but larger than any of the species found in the Paris gypsum. With these are several species of the genus _Oreodon,_ Leidy, uniting the characters of pachyderms and ruminants also; _Eucrotaphus,_ another new genus of the same mixed character; two species of rhinoceros of the sub-genus _Acerotherium,_ a Lower Miocene form of Europe before mentioned; two species of _Archæotherium,_ a pachyderm allied to _Chæropotamus_ and _ Hyracotherium_; also _Pæbrotherium,_ an extinct ruminant allied to _Dorcatherium,_ Kaup; also _ Agriochoerus,_ of Leidy, a ruminant allied to _ Merycopotamus_ of Falconer and Cautley; and, lastly, a large carnivorous animal of the genus _Machairodus,_ the most ancient example of which in Europe occurs in the Lower Miocene strata of Auvergne, but of which some species are found in Pliocene deposits. The turtles are referred to the genus _Testudo,_ but have some affinity to _Emys._ On the whole, the Nebraska formation is probably newer than the Paris gypsum, and referable to the Lower Miocene period, as above defined. [1] Bulletin, 1856, Journ., vol. xii, p. 768. [2] Heer “Miocene baltische Flora” and “Fossil-flora von Alaska” 1869. [3] D’Archiac Monogr., pp. 79, 100. [4] Pengelly, preface to The Lignite Formation of Bovey Tracey, p. xvii, London, 1863. [5] Philos. Trans., 1863. Paper by W. Pengelly, F.R.S., and Dr. Oswald Heer. [6] Quart. Geol. Journal, 1851, p. 19. [7] Quart. Geol. Journal, 1851, p. 90. [8] David Dale Owen, Geol. Survey of Wisconsin, etc., Philad., 1852. CHAPTER XVI. EOCENE FORMATIONS. Eocene Areas of North of Europe. — Table of English and French Eocene Strata. — Upper Eocene of England. — Bembridge Beds. — Osborne or St. Helen’s Beds. — Headon Series. — Fossils of the Barton Sands and Clays. — Middle Eocene of England. — Shells, Nummulites, Fish and Reptiles of the Bracklesham Beds and Bagshot Sands. — Plants of Alum Bay and Bournemouth. — Lower Eocene of England. — London Clay Fossils. — Woolwich and Reading Beds formerly called “Plastic Clay.” Fluviatile Beds underlying Deep-sea Strata. — Thanet Sands. — Upper Eocene Strata of France. — Gypseous Series of Montmartre and Extinct Quadrupeds. — Fossil Footprints in Paris Gypsum. — Imperfection of the Record. — Calcaire Silicieux. — Gres de Beauchamp. — Calcaire Grossier. — Miliolite Limestone. — Soissonnais Sands. — Lower Eocene of France. — Nummulitic Formations of Europe, Africa, and Asia. — Eocene Strata in the United States. — Gigantic Cetacean.