TERTIARY. 423 



genus, Hytenodon. The true Carnivora are abundant and 

 \uru-d, including even a cat (Eusmilus) on both continents; 

 but the viverroids are confined to Europe. Among ungulates 

 the Perissodactyla include hornless rhinoceroses on both conti- 

 nents ; while there is a considerable advance in the line of the 

 horses in North America, and Titanotherium represents the 

 highest and last development of the peculiarly American family 

 of Titanotheriidae. Some of the primitive Artiodactyla attain 

 a large size and become of importance, such as Anthracotherium, 

 Hyopotamus, and Elotherium, both in Europe and America. The 

 early ruminants are also represented in Europe by such genera 

 as Ccenotherium and Amphitragulus ; while they occur in still 

 greater vanety in North America as Oreodonts (Oreodon and 

 Agriochoeras), primitive camels (Poebrotherium), and strangely 

 horned quadrupeds (Protoceras). The opossum (Didelphys) 

 appears for the last time in Europe ; so also do the freshwater 

 ganoid fishes, Amia and Lepidosteus. Among marine mammals, 

 Halitherium and Miosiren, from the neighbourhood of Mayence 

 and Antwerp respectively, are the earliest well-known examples 

 of the Sirenia. 



The Middle Miocene fauna is well known from numerous 

 localities in Europe, and of these some of the more classical 

 may be enumerated as follows: Sansan, Simorre, and Ville- 

 franche d'Astarac in Gers, France ; Leognan and Romans, 

 Gironde ; St Gaudens, Haute Garonne ; La Grive-St-Alban, 

 Isere ; Montpellier, Herault ; Kapfnach, Chauxdefonds, and 

 Elgg, in Switzerland; Georgensgmiind, in Bavaria; Steinheim, 

 in Wiirtemberg; and Monte Bamboli, in Tuscany. In North 

 America the John Day Formation of Oregon and Montana is 

 supposed to furnish a nearly equivalent, though distinctly more 

 ancient assemblage of mammals. The most remarkable feature 

 of this fauna in Europe is the sudden appearance of the Pro- 

 boscidea (Dinotherium and Mastodon) and the true apes (Oreo- 

 pithecus, Dryopithecus). It is also interesting as comprising the 

 earliest known deer with antlers (Dicroceros), and the earliest 

 rhinoceroses with a horn. The Carnivora are noteworthy as 

 including a series of genera intermediate between the dogs 

 and bears (Amphicyon, Hycenarctos). In North America there 



