Aimed at students and general readers, this reader presents accessible half-hour chapters on lower forms of animal life, from microscopic protozoans through sponges, corals, echinoderms, worms, mollusks, crustaceans, and insects. Each chapter combines clear descriptions of structure, behavior, life cycles, and habitats with practical observations, illustrative anecdotes, and plates to aid visual understanding. Emphasis falls on economic relations and regional faunas, including Pacific coast species, while technical classification is minimized in favor of observational habits, collecting tips, and explanations suited for school use or self-study.