Speculates why animals have not developed wheels in place of inefficient legs. One study cited suggests three reasons why animals are better off without wheels: wheels are efficient only on hard surfaces, limitation of wheeled motion due to vertical obstructions, and the problem of turning in spaces cluttered with obstacles. (JN)

Water striders are insects that walk and run on the surface of water. Discusses the morphology, physiology, and behavior of these insects. Includes diagrams of stages in the movement of a typical strider. (JN)