defense; (c) defense of young; (d) rivalry; (e) adjustment to surroundings.

For the purpose of capture of their prey, most carnivorous animals are provided with strong claws, sharp teeth, hooked beaks, and other structures familiar to us in the lion, tiger, dog, cat, owl, and eagle. Insect-eating mammals have contrivances especially adapted for the catching of insects. The ant-eater, for example, has a long sticky tongue which it thrusts forth from its cylindrical

snout deep into the recesses of the ant-hill, bringing it out with its surface covered with ants. Animals which feed on nuts are fitted with strong teeth or beaks for cracking them. Strong teeth are found in those fishes which feed on crabs, or sea urchins. Those mammals like the horse and cow, that feed on plants, have usually broad chisellike incisor teeth for cutting off the foliage, and teeth of very similar form are developed in different groups of plant-eating fishes. Molar teeth are found when it is necessary that the food should be crushed or chewed, and the sharp canine teeth go with a flesh diet. The long neck of the giraffe enables it to browse on the foliage of trees in grassless regions.

FIG. 189. The brown pelican, showing gular sac which it uses in catching and holding fishes for its food.

Insects like the leaf-beetles and the grasshoppers, that feed on the foliage of plants, have a pair of jaws, broad but sharply edged, for cutting off bits of leaves and stems. Those which take only liquid food, as the butterflies and sucking bugs, have their mouth parts modified to form a slender, hollow sucking beak or proboscis, which can be thrust into a flower nectary, or into the green tissue of plants or the flesh of animals, to suck up nectar or plant sap, or blood, according to the special food habits of the insect. The honey-bee has a very

complicated equipment of mouth parts fitted for taking either solid food like pollen, or liquid food like the nectar of flowers. The mosquito has a "bill" composed of six sharp, slender needles for piercing and lacerating the flesh, and a long tubular under lip through which the blood can flow into the mouth. Some predaceous insects, as the praying horse (Fig. 38), have their fore legs developed into formidable grasping organs for seizing and holding their prey.

PG. 190.-Ant-lion larva plowing its way through the sand (upper figure), while another is commencing the excavation of a funnel-shaped pit similar to one on right. (Photograph by A. L. Melander and C. T. Brues.)

For self-protection the higher animals depend largely on the same organs and instincts as for the securing of food. Carnivorous beasts use tooth and claw in their own defense as well as in securing their prey, but these as well as other animals may protect themselves in other fashions. Many of the higher animals are provided with horns, structures useless in procuring food, but effective as weapons of defense. Others defend themselves by blows with their strong hoofs. Among the reptiles and fishes and even among the mammals, the defensive coat of mail is found in great variety. The turtle, the armadillo, the sturgeon, and gar pike, all these show the value of defensive armature, and bony shields are developed to a still greater

degree in various extinct types of fishes. The crab and lobster with claws and carapace are well defended against their enemies, and the hermit crab, with its trick of thrusting its unprotected body within a cast-off shell of a sea snail, finds in this instinct a perfect defense. Insects also, especially beetles, are protected by their coats of mail. Scales and spines of many sorts serve to defend the bodies of reptiles and fishes, while feathers protect the bodies of birds and hair those of most mammals.

The ways in which animals make themselves disagreeable or dangerous to their captors are almost as varied as the animals themselves. Besides the teeth, claws, and horns of ordinary attack and defense, we find among the mammals many special structures or contrivances which serve for defense through making their possessors unpleasant. The scent glands of the skunk and its relatives serve as examples. The porcupine has the bristles in its fur specialized as quills, barbed and detachable. These quills fill the mouth of an attacking

FIG. 191.-Scorpion showing the special development of certain mouth parts (the maxillary palpi) as pincerlike organs for grasping. On the posterior tip of the body is the poison sting.

wolf or fox, and serve well the purpose of defense. The hedgehog of Europe, an animal of different nature, being related rather to the mole than to the squirrel, has a similar armature of quills. The armadillo of the tropics has movable shields, and when it withdraws its head (also defended by a bony shield) it is as well protected as a turtle.

The turtles are all protected by bony shields, and some of them, the box turtles, may close their shields almost hermetically. The snakes broaden their heads, swell their necks, or show their forked tongues to frighten their enemies. Some of

them are further armed with fangs connected with a venom gland, so that to most animals their bite is deadly. Besides

FIG. 192.-Cocoon enclosing a pupa of the great Ceanothus moth, Samia ceanothi, spun by the larva before pupation.

its fangs the rattlesnake has a rattle on the tail made up of a succession of bony clappers, modified vertebræ, and scales,

by which intruders are warned of its presence. This sharp and insistent buzz is a warning to animals of other species and perhaps a recognition signal to those of its kind.

Even the fishes have many modes of self-defense through giving pain or injury to animals who would swallow them. The catfish or horned pout when attacked sets immovably the sharp spine of the pectoral fin, inflicting a jagged wound. Pelicans which have swallowed a catfish have been known to die of the wounds inflicted by the fish's spine. In the group of scorpion fishes and toad fishes are certain genera in which these spines are provided with poison glands. These may inflict very severe wounds to other fishes, or even to birds or man. One of this group of poison fishes is the nohi (Emmydrichthys). A group of small fresh-water catfishes, known as the mad toms, have also a poison gland photograph by Slinger- attached to the pectoral spine, and the sting is most exasperating, like the sting

land.)

of the wasp. The sting-rays (Fig. 194), of which there are many species, have a strong jagged spine on the tail, covered with slime, and armed with broad sawlike teeth. This inflicts a dangerous wound, not through the presence of specific venom, but from the danger of blood poisoning arising from the slime, and the ragged or unclean cut.

The poisonous alkaloids.

within the flesh of some fishes (Tetraodon, Balistes, etc.) serve to destroy the enemies of the species while sacrificing the individual. These alkaloids, most developed in the spawning season, produce a disease, known in man as ciguatera. This is rarely known outside of the tropics.

Many fishes are defended by a coat of mail or a coat of sharp thorns. The globe fishes and porcupine fishes are for the most part defended by spines, but their instinct to swallow air gives them an additional safeguard. When one of these fishes is disturbed it rises to the surface, gulps air until its capacious stomach is filled, and then floats belly upward on the water. It is thus protected from other fishes, though easily taken by man. The torpedo, electric eel, electric catfish, and star-gazer, surprise and stagger their captors by means of electric. shocks. In the torpedo or electric ray (Fig. 195), of which species are found on the sandy shores of all warm seas, on either side of the head is a large honeycomblike structure which yields a strong electric shock whenever the live fish is touched. This shock is felt severely if the fish be stabbed with a knife or metallic spear. The electric eel of the rivers of Paraguay and southern Brazil is said to give severe shocks to