THE LIFE OF MAMMALS 
Another elaborately armed form is the babirussa, or ‘deer 
hog,” a big, bluish, almost hairless hog of the wet jungles 
of Celebes and Boru islands, whose tusks grow to 
an enormous length, sometimes a foot or more 
outside the mouth. This is due to the fact that they do not 
strike against one another, for the upper pair grow right up 
through the upper lip, and grow 
continuously, unchecked by the 
wear of any use, till they strike 
the forehead and curl down 
again. It, like the wart hog, is 
aside from the typical line of 
swine; but it makes good pork, 
and is an object of local sport. 
Babirussa. 
In the hippopotamus we have 
THE BaBIRUssa. a member of the swine group 
very interesting to the zodlogist, as one of those curious survi- 
vals of an ancient type alongside rapidly progressive relatives. 
Hippopdta= It is, indeed, as Schmidt “* points out, the only liv- 
mus. ing representative of the hoofed animals with tuber- 
culate teeth which has preserved the old structure of the limbs 
pretty well unchanged. 
“The early Tertiary ancestors of the ruminants,” he remarks, “‘had to 
dwell principally in waters and on marshy ground. Their descendants 
adapted themselves gradually to life on dry ground, and this is connected 
with the advantageous reduction of the toes. The hippopotamus family 
has taken an opposite course; from being an animal that liked the marshy 
soil of the primeval forests it has become an aquatic creature, and accord- 
ingly has preserved the completeness of hand and foot, the four toes almost 
fully developed.... If by some extravagant flight of the imagination we 
could conceive the existence of a one-toed leviathan, the very fact of its 
possessing a one-toed foot would be the cause of its speedy extinction. As 
regards dentition also, the hippopotamus shows signs of being geologically 
very old.” 
350 
