Page:Popular Science Monthly Volume 16.djvu/813

 and teeth for grasping food. A full description of these organs more properly belongs to the subject of eating food. Gnawing animals, like the rabbit, have the four front teeth, incisors, acting as chisels. In the hippopotamus the prehensile teeth form tremendous shears for cutting plant-stems.

Beasts of prey use jaws or feet, or both; but, to bring the prey within reach of either organ, requires keen senses to discover, and



craftiness and speed to catch them. Animals of the dog tribe seize with the jaws; those of the cat tribe use all four feet. The supple paw, with its retractile claws, is highly fitted for grasping and tearing, as well as for silent, stealthy tread. The cat's tongue is armed with spiny, recurved papillæ, to lap blood or scrape flesh from bones.

Monkeys also employ all their feet for grasping; and, in common with those mammals that can sit on their hind-limbs, such as the squirrel, rat, kangaroo, and bear, carry food to the mouth with the fore-limbs; and some monkeys use the sensitive tips of their long tails to draw fruit from crevices or holes. The strainer of the Greenland whale has been described. A shovel-bill is the appliance of the duck-mole.

Only reference can here be made to the adaptation of mammals to the element in which their food exists. The whale, seal, hippopotamus, and duck-mole, find sustenance in the water. In the ground burrows the mole; the squirrel and sloth inhabit the trees, while the bat searches the air. Thus every element contains representatives of this highest animal group.

Prehension of food is so various in means and methods that no universal laws regarding it can be formulated. It can not form a basis of classification, seeming to have little or no discovered relation to animal rank. However, the subject is of greatest interest; and