MAMMALIA. 



31 



Nothing is known of the direct ancestors of the American Table-case 

 peccaries (Dicotylidse). Eemains of the typical Dicotyles 7 - 

 from the caverns of Brazil are exhibited in Table-case 7. 



Among earlier animals allied to the pigs, the large 

 Elotherium, from the Oligocene and Miocene of Europe and 

 North America, is especially remarkable. As shown by 

 remains in Pier-case 13, it had only two toes, with the 

 merest rudiment of the outer toes. Listriodon, from the 

 Miocene of Europe and India, has a skull like a pig, but 

 grinding teeth with cross-ridges like those of a tapir (Table- 

 case 7). Hyotherium is provided with large upper canine 

 teeth (Table-case 7). Chmropolamus is represented in the 

 same Case by jaws and teeth from the Upper Eocene of the 

 Isle of Wight and of France. 



In these early allies of the pigs the molar teeth are 

 nearly square and bear regularly arranged cusps or ridges. 

 In some of them the tooth-cusps tend to become crescent- 

 shaped, and hence make an approach to the trenchant 

 crescentic (" selenodont ") cusps of the teeth in the higher 

 Artiodactyla which chew the cud (" ruminants "). One 

 family, that of the Anthracotheriidse, with molar teeth in 

 this condition, arose in the Upper 

 Eocene and was represented during 

 the Oligocene period by many moder- 

 ately large species, which ranged 

 over the greater part of the northern 

 hemisphere. These were stoutly- 

 built animals, some probably much 

 resembling the pigs in outward 

 aspect, others more nearly allied to 

 the hippopotamus. All of them have 

 four or five separate toes. Anihra- 

 cotherium (" coal beast ") itself, which 

 is well represented in Table-case 7, 

 is so called from the circumstance 

 that its remains were first discovered 

 in the lignite or brown-coal of Savoy. 

 It is chiefly found in the Oligocene 

 of Europe, but also seems to occur 



in the corresponding deposits in Dakota, U.S.A., while a 

 few teeth have been assigned to it from the Lower Pliocene 

 Siwalik Formation of India. The European A. magnum 

 must have been as large as a rhinoceros. Hyopotamus is 

 another genus, of which the detached teeth (Fig. 20) are 



Fig. 20. — Grinding surface 

 of third right upper true 

 molar tooth of Hyopo- 

 tamus bovinus, from the 

 Oligocene of Hemp- 

 stead, Isle of Wight; 

 nat. size. (Table-case 7.) 



