AT a joint meeting of the Sections of Geology and Anthropology of the British Association at Bristol, Prof. G. B. Barbour, of the Department of Geology, Yenching University, gave a very interesting lecture on “The Geological Background of Peking Man (Sinanthropus)” Chou-kou-tien, where Sinan-thropus was discovered in an abandoned limestone quarry, overlooking the re-entrant margin of the Yellow River delta plain, lies 37 miles south-west of Peiping (Peking), on a branch of the Peking-Hankow railway. The fossiliferous deposit was first reported by J. Gunnar Andersson in 1921, and in the following year Otto Zdansky discovered mammalian material, reporting in 1926 that it contained hominid teeth. In 1928 B. Bohlin, C. C. Young, and W. C. Pei found an adult right ramus, with three molars in situ, together with part of another jaw and many skull fragments. In 1929 W. C. Pei, a young geologist on the staff of Yenching University, discovered first fragments of a skull, since reconstructed, and later an uncrushed adult skull. This latter discovery occurred at 4 P.M. on Dec. 2, the last day on which it was possible to work because of the increasingly wintry weather. The skull was embedded in a travertine matrix, and Prof. Barbour described the infinite care and skill with which Dr. Davidson Black removed the matrix, taking repeated casts and photographs, in an effort to ensure that the fullest records should be available for future workers.