In dealing with Stone Age industries it is a sound principle to judge by the mass from a single site, as exceptional forms may be purely accidental and differ in date from similar pieces found elsewhere. But this method does not justify the neglect of rare specimens, which may unexpectedly amplify or correct the impression gained by even the most careful study of a large and commonplace series. To emphasize the occasional value of exceptional products, several specimens for which special importance is claimed have been selected during the last few years, and the Society is indebted to their respective owners for putting them on exhibition when this paper was read. Some have since been generously presented to the British Museum.