28 THE AGE OF MAMMALS 



10. Perissodactyla. Odd-toed, hoofed iiiaminals, Lower Eocene to 

 recent times, including tapirs, horses, rliinoceroses, and the extinct 

 , j'fil'i^'otheres, titanotheres, lophiodonts, etc. 



17. Ancylopoda. Closely related to the Perissodactyla. Middle Eocene 



to Upper Miocene times, with hoofs secondarily modified into claws, 

 partly for digging. 



B. Prohabhj of African Orujin. 



18. Proboscidea. Mastodons and elephants. Upper Eocene to recent 



times. 



19. Barytheria. Inclnding only one (discovered) large, peculiar herlii- 



vore, of the Lower Oligocene of North Africa. 



20. SiRENiA. Sea-cows or manatees, and dugongs. A liighly modified 



aquatic offshoot of the hoofed mammals. Upper Eocene to recent 

 times. 



21. Hyracoidea. The dassies and conies of Africa and Syria, small 



rock and tiee-living hoofed animals. Upper Eocene to recent times. 



22. Embrit HOPOD A. Including the " Arsinoi'theres " of the Upper Eo- 



cene and Oligocene of northern Africa only. 



2. NEOGiEAN HOOFED MAMMALS OR NOTOUNGULATA 



i.e. of South America. 



23. HOMALODOTHERIA. Including //owr//o^/rt?/;enMm and others. Penta- 



dactyl, secondarily clawed mammals. Teeth in continuous series. 

 Eocene to JNIiocene, South America. 



24. TOXODONTIA. Including the protypotheres, typotheres, nesodonts, 



and toxodonts. Eocene to Pleistocene, South Amei'ica. Molars with 

 flattened outer wall, more or less rhinocerotoid. Incisors often 

 enlarged. 



25. ASTRAPOTHERlA. Including the rhinoceros-like astrapotheres. 



Chiefly Miocene, South America. Upper canines forming elongate 

 tusks. Limbs pillar-like. 



26. LiTOPTERNA. Including light-limbed, three-toed, and virtually one- 



toed forms, some resembling three-toed horses. Eocene to Pleistocene, 

 South America. 



27. Pyrotheria. Including 'dijirotodont' forms with crested masto- 



don-like molar teeth. Eocene, South America. Limbs pillar-like. 



D. CETACEA, or whales, aquatic mammals probably derived from the 

 Unguiculate Division. 



28. Zeuglodontia. Primitive Eocene whales, transitional in certain 



characters to primitive carnivores. 



29. Odontoceti. Toothed whales, including the extinct squalodonts, the 



river and marine dol2:)hins, the belugas and narwhals, the beaked 

 whales, and the sperm whales. 



30. M Y S T A c c E T I. Whalebone whales, including the right whales, the 



humpbacked whales, and the fin -backed whales. 



