In Part III the isolation of hyoscine, hyoscyamine, norhyoscine, and apohyoscine from the leaves of Datura sanguinea R. and P. was described and the occurrence of other bases noted. We record here the characterisation of two of these new bases. (-)-3α-Tigloyloxy-6β-acetoxytropane has been identified as a component of the alkaloidal mixture of Datura sanguinea leaves and young stems. Its structure was indicated by spectroscopy and by hydrolysis and confirmed by partial synthesis. 3α-Acetoxytropane, not previously recorded as a natural product, has also been isolated from the same plant material.