SUBORDER D ARTIODACTYLA 177 



exceedingly large, strongly curved, triangular, with edges sharpened through wear of 

 posterior surface. Inferior incisors cylindrical, very long, rootless, directed forward. 

 Carpals, tarsals and metapodials distinct. Feet tetradactyl, the lateral digits but little 

 more slender and shorter than the medians. Terminal phalanges with nail-like 

 hoofs. 



The single existing genus of this family is confined to tropical Africa. 

 Fossil representatives are found in the Pliocene and Pleistocene of Asia, 

 Africa, and Europe. 



The genus Hippopotamus Linn. (Fig. 240) is divided into two subgenera, 

 Hexaprotodon and Tetraprotodon Falconer, these being based on the number of 

 incisor teeth present. Lower Pliocene ; India. H. sivalensis Falconer and 

 Cautley. One species, also, in the Pliocene of Algiers and Egypt. H. hip- 

 ponensis Gaudry. Li the Pliocene of Val d'Arno. II. major and H. pentlandi 

 Falconer, which also occur in the Lower Pleistocene of Europe, both being 

 closely allied to the existing H. amphibius Linn. In the Pleistocene of Algiers 

 are several species ; also in the late Pleistocene of Madagascar is a small very 

 abundant form, H. madagascariensis Grandidier. One small species also from 

 Malta, Crete and Cyprus. H. minutus Blainv. In the Pleistocene of Java is 

 found H. sivajavanicus Dubois. 



Tribe 2. BUNOSELENODONTIA. 



Family 4. Anthracotheriidae Leidy.^ 



Extinct artiodactyls with complete dentition. Dental formula : ' ' ' ' • Superior 



molars with four main cusps and one intermediate tubercle in the anterior half of the 

 tooth ; inferior molars with crescentic external cusps, conical on the inside. Premolars 

 short, the three anterior ones monocuspid, usually separated from, the canine by a 

 diastema; only the last premolar with a secondary cusp. Carpals, tarsals and 

 metapodials not co-ossified. Feet tetradactyl, the lateral digits more slender and 

 shorter than the median ones. 



The Anthracotheriidae form a primitive group of artiodactyls which were 

 especially abundant in Europe, but were more sparingly distributed in North 

 America, northern Africa and India. The oldest remains are found in the 

 Upper Eocene Bohnerz and Phosphorites, the chief deposits for Anthracotherium 

 being the Oligocene. The latest forms became extinct in the Miocene. 



Anthracotherium Cuvier (Heptacodon, Octacodon Marsh) (Fig. 241). Superior 

 molars broader than long, with four V-shaped or conical cusps and an anterior 

 crescentic intermediate cone. Inferior molars quadritubercular, the last tooth 

 with a strong talonid. Incisors above and below spatulate, tapering. Canine 

 very powerfully developed. Diastema small. Abundant in the Oligocene of 

 Europe, especially in coal-bearing deposits. The species vary in size between 



^ Cooper, O. Forster, Palaeont. Tndica, n.s., vol. viii., no. 2, 1924. — Filhol, IJ., Mammiferes 

 fossiles de Ronzon. Ann. Soc. Geol., 1882, p. 85. — Kowalevsky. IV., On the Osteology of the 

 Hyopotamidae. Philos. Trans. 1873. — Anthracotherium. Palaeontographica, 1873, vol. xxii. — 

 Scotl, W. B., Structure and Pi,elationship of Ancodus. Journ. Acad. Nat. Sci. Philad. 1895. — 

 Schmidt, M., Paarhufer der tiuvioiiiarinen Schichten des Fajum. Geol. u. Palaeont. Abhandl., 

 1913. — Stehlin, H. G., Revision der europaischen Anthracotherien. Verhandl. naturf. Ges. 

 Basel, 1910. 



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