An engaging introduction to the invertebrates, beginning with the simple amoebæ and concluding with the complex centipedes, spiders, and six-legged insects. In between the reader encounters a number of groups of animals of increasing complexity, beginning with the living sponge, the traveling jelly-fish, and the wondrous coral-builders, then passing on to the star-fish, sea-urchins, and sea-cucumbers. Next come mussels and snails, cuttle-fish and oysters, followed by creeping worms, and arriving at last at the joint-legged division including crabs that live in the water, as well as the aforementioned centipedes, spiders, and insects that breathe only in the air, which comprise more than four-fifths of the living beings on our globe. All creatures are described in such a way as to arouse an abiding interest in them and their behavior. Dozens of labeled ink drawings suitable for copying into notebooks are included, encouraging close attention to details.