290 THE LIVING ANIMALS OF THE WORLD 
may seem when viewed from behind 
the bars of its den in a zoological 
garden, it is nevertheless true that, 
when these animals have been 
banished from an African river by 
the progress of civilisation, that river 
has lost one of its highest charms 
and greatest ornaments. 
The Pycmy or LIBERIAN HIp- 
POPOTAMUS is confined to Upper 
Guinea, and, compared with its only 
existing relative, is a very small ani- 
mal, not standing more than 2 feet 
6 inches in height, and measuring 
less than 6 feet in length. In weight 
a full-grown specimen will scale about 
400 lbs. But little is known of 
the habits of this rare animal, speci- 
mens of which, I believe, have never 
been obtained, except by the German 
naturalists Herrn Biittikofer and 
Jentink. When alive, the colour of 
a ~ 5 “ a = . * 
© Photo by York & Son] i the skin of the pygmy hippopotamus 
MALE AND.FEMALE HIPPOPOTAMUSES is said to be of a greenish black, 
hangi h - 7 
A hippopotamus is almost inseparable from the water ; it never goes farther away c anes on the under parts to 
than possible from a river or lake yellowish green. The surface of the 
skin is very shiny. This species, 
unlike its giant relative, does not congregate in herds, nor pass its days in rivers or lakes, but 
lives in pairs in marshes or shady forests. It sleeps during the day, and at night wanders 
over a great extent of country, eating grass, wild fruits, and the young shoots of trees. Its 
flesh is said to be very succulent and much esteemed by the natives. 
A hippopotamus, apparently of the same species as that now found in Africa, formerly 
inhabited the Thames Valley. Great quantities of fossil remains of another species are also 
found in the island of Sicily. The bones found in England are mainly in the river gravel 
and brick earth of the south and midland districts of England. This seems to show that at 
the time when the animal existed our rivers must have been open all the year, and not 
ice-bound, for it is certain that no hippopotamus could live in a river which froze in winter. 
Yet among the remains of these animals are also found those of quite arctic species like the 
Musk-ox and the Reindeer, together with those of the Saiga Antelope, an inhabitant of the 
cold plateau of Tibet. The problem is: How could these creatures, one a dweller in warm 
rivers and the others inhabitants of cold arctic or sub-arctic regions, have existed together, 
apparently onthe same area of ground? The answer, which does not seem to have occurred 
to naturalists who have discussed the question, seems to be plain enough. Any one who 
knows the conditions of the great rift valleys of Central Africa has the key to the solution 
of the puzzle. There was probably a very great difference in the vertical plane. Deep in 
the rift was probably a warm river, while above it may have been mountains from 10,000 
to 20,000 feet high, with snow on the summits and glaciers in their valleys. On these cold 
and arctic heights the reindeer and the musk-ox would find congenial homes. Thousands 
of feet below, in the hot and narrow valley, the hippopotamus would revel in a warm and 
steamy climate. This is what actually occurs in the rift valleys of Central Africa, where 
the hippopotamus swims in rivers that are at no great distance from snow-covered and ice- 
capped mountains. 
