xl ARTIODACTYLES OF MADAGASCAR BGP E 
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 
Peceary 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.' 
Group I.—SUINA. 
Fam. 1. Hippopotamidae.—The family Hippopotamidae con- 
tains of existing genera only Hippopotamus, for the Liberian dwart 
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? 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 imhabited 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 
de 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. 
VOL. X qt 
