xi ARTIODACTYLES OF MADAGASCAR 273 



in Europe, Asia, and Africa. The Neotropical region has no Oxen, 

 or Sheep, or Antelopes. The latter are confined to Africa, Asia, 

 and certain parts of the Palaearctic region ; they are vastly more 

 prevalent in Africa, where they take the place of the totally 

 absent Deer. The Pig tribe is almost entirely Oriental and 

 Ethiopian in distribution, only one form, the European Wild Boar, 

 ranging into the Palaearctic region; and the two species of 

 Peccary are found in both North and South America. Broadly 

 speaking, the Ethiopian region is the headquarters of the Artio- 

 dactyla. But the great island of Madagascar has but one form of 

 Artiodactyle, a Pig of the genus Potamochoerus. 1 



GROUP I.SUINA. 



Fam. 1. Hippopotamidae. The family Hippopotamidae con- 

 tains of existing genera only Hippopotamus, for the Liberian dwarf 

 Hippopotamus is not now regarded, as it was formerly, as the type 

 of another genus, Choeropsis. The reasons for its former separa- 

 tion were the loss of the outer pair of incisors and the different 

 proportions of various parts of the skull. This little Liberian 

 animal has, however, been shown by Sir W. Flower 2 to possess 

 the missing incisors occasionally; and as to the proportions of 

 the skull, it is exceedingly common for small animals to vary from 

 larger relatives in this way. Hence, considering the characteristic 

 features of the Hippopotamus and the fewness of species, it seems 

 unnecessary to divide it up further. We shall therefore only 

 recognise one genus. 



The Hippopotamus at present is African in range, and confined 

 to that continent. But quite recently it inhabited Madagascar ; 

 and further back still in time the existing African species, 

 H. amphibius, ranged into Europe ; there were also Indian forms, 

 which were contemporary with the Stone - age man. The 

 Common Hippopotamus is a great thick-skinned beast with but 

 few hairs. It has four toes on each foot, a complex stomach, but 

 no caecum. The strong incisors continue growing through life, as 

 .do the great canines. The number of incisors is two on each 

 side of each jaw. Some of the extinct species had six in each 



1 Bones of Hippopotamus, however, indicate the very recent occurrence of that 

 animal in Madagascar. 



2 "On the Pygmy Hippopotamus of Liberia,*' Proc. Zool. Soc. 1887, p. 612. 

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