Abdomen (ăb-dō´mĕn).—In mammals, that portion of the body-cavity which is separated from the thorax or chest by the diaphragm. In insects the third or last portion.
Ametabolic (ȧ-mĕt´a-bŏl´ĭk).—Referring to insects and other animals which do not undergo a metamorphosis, or change of form.
Amoeba (ȧ-mē´bȧ).—One of the Protozoa that is continually changing its shape.
Amorphous (ȧmŏr´fŭs).—Without a definite figure; shapeless; especially applicable to sponges.
Amphibia (ăm-fĭb´ĭ-ȧ).—A class of vertebrates, breathing in water while young and in air when mature. The term amphibious is applied to fishes, molluscs, etc., that are capable of changing the nature of their respiration at will.
Annelida (ăn-nĕl´ĭ-dȧ).—Articulate animals whose bodies possess no jointed members, as the leech, and worm tribe.
Annulate (ăn′u-lāt).—Animals whose bodies are composed of a series of ring-shaped divisions.
Anthropoid (ăn-thrō-poid).—The highest order of apes.
Apterous (ăp´tĕr-ŭs).—Destitute of wings.
Arachnida (ȧ-răk´nĭ-dȧ).—Articulate animals with legs, but without wings, including spiders, mites, scorpions, etc.