THE POPULATION II CEPHEIDS.

Several of the spectral and dynamic characteristics of Population II Cepheids are described, based on a number of recent observations. The stars are categorized according to period distribution, light curves, velocity curves, chemical composition, galactic kinematics, atmospheric shock waves, and location in the color-magnitude diagram. The relationship of normal Population II Cepheids to similar variable stars such as the RV Tauri is also discussed.