ANCIENT AND MODERN HIPPOPOTAMUSES 269 
in the same country at the same time, is very difficult to 
understand. If the hippopotamus had been different from 
the living African one, we might have regarded it as a 
terrestrial species, like tHat of Liberia, and thus perchance 
capable of standing a colder climate; but being identical 
with the former, we are perforce compelled to believe 
that its habits were similar, and that in its home the 
rivers must have been more or less free from ice through- 
out the year. Whatever may be the true explanation of 
the difficulty, it is pretty clear that no theory of summer 
and winter migrations will hold good, as the hippopotamus 
is essentially a resident animal. 
Returning once more to Africa, we may notice that in 
Algeria, where the genus is now unrepresented, a small 
species (H. hipponensis) flourished during the Pleistocene 
period ; this species being distinguished by carrying three 
pairs of lower incisor teeth, which differed from those of 
other members of the genus in having their enamel 
smooth and their extremities somewhat expanded, thus 
approximating to the corresponding teeth of the pigs. 
Equally noteworthy is the occurrence of another species, 
Lemerle’s hippopotamus (H. Jlemerlet), in Madagascar, 
where its remains are common in the great marsh of 
Ambulisatra. Somewhat intermediate between the common 
and the Siwalik species, this rather small hippopotamus 
had sometimes three and sometimes two pairs of lower 
incisors. Certain traditions current among the Malagasy 
suggest that this species may have lived within the historic 
period, and it may even be one of several mysterious animals 
alluded to by an early European voyager. 
In addition to the common species, Southern Europe, 
inclusive of Cyprus, Malta, and some of the other Medi- 
terranean islands, was the home of several smaller species, 
