214 



GEOGRAPHICAL ZOOLOGY. 



[part IV. 



only. The hornless Acerothermm is Miocene only, in both 

 countries. Otlier genera are, Lcptodon from Greece, and Hyra- 

 codon from Nebraska, both of JMiocene age. More than 20 

 •species of extinct rhinoceroses are known, and one has even been 

 found at an altitude of 16,000 feet in Thibet, 



Family 4(3.— niPPOrOTAMID.E. (1 Genus, 2 Species.) 

 Gexei!al Distribution. 



NrOTUOPR'AL 

 St;B-RE0ION:i. 



Neaectic 

 Sub-regions. 



Pal.earctic 

 sub-iiegion.s. 



Ethiopian 

 Sub-regions. 



Oriental 

 Sub-regions. 



Australian 

 Sub-regions. 



Living Species. 

 1.2.3 



Extinct Specie.^. 

 1.2 



1-3 



The Hippopotamus inhabits all the f re.it rivers of Africa; a 

 distinct species of a smaller size being found on the west coast, 

 and on some of the rivers flowing into Lake Tchad, 



Fossil Hippopotami. — Eight extinct species of Hip2?opotamvs 

 are known from Europe and India, the former Post-pliocene or 

 Pliocene, the latter of Upper ]\Iiocene age. They ranged as far 

 north as the Thames valley. An extinct genus from the Siwalik 

 Hills, Merycopotcumis, according to Dr. Falconer connects Hippo- 

 2Jotamus with Anthracothcriv.m, an extinct form from the Miocene 

 of Europe, allied to the swine. 



Family 47. — 8UTD.E. (5 Genera, 22 Species.) 



Tlie Swine may be divided into three well-marked groups, 

 frum peculiarities in their dentition. 1. The I)icotylinie, or 



