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 (//. 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. lemerlei\ 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, 



