In Asia many of the males, and all the females, are without tusks, but in Africa both sexes are provided with these weapons.

The enamel in the molar teeth is arranged differently in the two species.

By an admirable provision, new teeth constantly come up at the part where in man the wisdom teeth appear, and these push the others along, and out at the front end of the jaws, thus keeping the molars sound by renewal, till the animal attains a very great age.

The tusks of animals from dry rocky countries are very munch more dense and heavier than those from wet and marshy districts, but the latter attain much the larger size.
The Shire marshes support prodigious numbers of many kinds of water-fowl.
An hour at the mast-head unfolds novel views of life in an African marsh.
Near the edge, and on the branches of some favourite tree, rest scores of plotuses and cormorants, which stretch their snake-like necks, and in mute amazement turn one eye and then another towards the approaching monster.

By and-by the timid ones begin to fly off, or take "headers" into the stream; but a few of the bolder, or more composed, remain, only taking the precaution to spread their wings ready for instant flight.