HIPPOPOTAMI. 373 



two species Macrauchenia Patachonica and M. Boliviensis, remnants 

 of the remarkable South American Pliocene fauna. With certain 

 characters approximating it to the camel and horse, it is claimed 

 by Burmeister that the animal was provided with a proboscidiform 

 trunk. 



XJngulata Artiodactyla (Even-toed hoofed-animals). — The 

 members of this sub-order, both recent and fossil, tire conveniently 

 divided into two groups — those which, like the hog, have the 

 grinding surfaces of the molar teeth tuberculated (Bunodonta), 

 and those, in which these surfaces are crescentically ridged, as in 

 the sheep, ox, deer (Selenodonta). The first of these groups, the 

 Bunodonta, comprises but two families, the swine (Suidae) and 

 the hippopotami (Hippopotamidae). 



Of the hippopotami there are, as generally recognised, only 

 two species, the common form (H. amphibius), which until re- 

 cently inhabited most of the larger streams of the continent of 

 Africa, from the Congo, Senegal, and Zambesi to the Nile, but 

 whose domain has of late been rapidly narrowing (completely ex- 

 cluded from the Egyptian Nile), and the West African Choeropsis 

 Liberiensis, a comparatively small animal, differing primarily from 

 the first in the possession of only a single pair of incisors in the lower 

 jaw instead of two pairs. A third species, whose remains have 

 been found sub-fossil in the swamp deposits of the island of Mada- 

 gascar (in association with the giant ^pyornis), and which may 

 consequently be classed with the recent period, has been described 

 by Goldberg (1883) under the name of H. Madagascariensis. The 

 common species of hippopotamus represents one of the most an- 

 cient of the mammalian types entering into the formation of the 

 modern fauna, it being one of the very few forms which survived 

 the Pliocene period up to the present day. Its range was formerly 

 very much greater than it now is, and even as late as the Post-Plio- 

 cene it appears to have inhabited Europe as far north as Northern 

 Wales, where its remains have been found associated with human 

 implements. Seven other species of the genus have been de- 

 scribed from the Pliocene and Post-Pliocene deposits of Europe 

 and India, but none have so far been recorded from America. — The 

 pigmy hippopotamus of Malta (H. minutus) appears to have been 

 closely allied to, if not identical with, the living Liberian spe- 

 cies. 



