The systems of bright lunar rays all are connected either with ringed plains or with smaller craters which brighten under a high sun. None are associated with the mountain-walled plains. The darker rings do not show ray systems, but in general the brighter ones do. The size of the ring is not closely correlated with the magnitude of the system. Two rings in the area around Furnerius are small and Kepler is not a large ring, yet each has a welldeveloped ray system.