THE United States Coast and Geodetic Survey, in co-operation with Science Service and the Jesuit Seismological Association, has determined the epicentres of two recent South American earthquakes. From seismographic reports from twenty-two observatories, the epicentre of the earthquake of May 14 at 2h. 13.3m. U. T. provisionally turned out to be near lat. 1° S., long, 79° W. This is near the town of Riobamba, in Ecuador. From reports from five stations, the provisional epicentre of the earthquake of May 14 at 8h. 39.0m. U. T. turned out to be on the bed of the Pacific Ocean,: off Tuniaco in Colombia. Soth epicentres are in well-known seismic regions.