Mescaline, anhalonine, lophophorine, pellotine, and anhalonidine were identified in alkaloid extracts of a prehistoric specimen of <i>Lophophora williamsii from a burial cave in west central Coahuila, Mexico. The speci-men was associated with radiocarbon dates of 810-1070 AD and was of the oldest materials ever submitted to alkaloid analysis. -- AATA