THE isolation1 of a precursor (I) of geijerene (11) from Geijera parvi$ora Lind. supports the view2 that elemane-type sesquiterpenes may arise by Cope rearrangements of terpenoid cyclodecadienes. We report that the sesquiterpene alcohol, elemol, is indeed such an artefact in one essential oil, and suggest that this may be generally true of elemol and the elemenes.

The range of (presumed) polyketide constituents in comatalid crinoids has been extended to include bianthronyls, meso-naphthodianthrones and sulphate esters of various of the polyketides. Several species of fish are deterred from eating food by the inclusion in it of these sulphates at the concentration found in crinoids. Sodium 2-hydroxy-anthraquinone sulphate and anthraquinone-2-suphonate were also active as antifeedants for the species tested.

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Varieties of the shrub Myoporum deserti A. Cunn. (Ellangowan poison bush), which causes heavy losses of stock in inland Australia, yield at least nine different essential oils, most of which are toxic. One oil from plant material of the Longreach chemical race from Blackall, Clermont, Hannaford, Longreach, Meandarra, Moree, and Roma contains the toxic furanoid sesquiterpene ketone, (-)-ngaione, as the principal constituent while two others (the Mitchell and the Blackall races) contain lesser proportions of ngaione. (-)-Ngaione comprises over half of the essential oil of a "greenish leaf" variety of Eremophila latrobei F. Nuell. and a low proportion of the oil of a "silver leaf" variety of the same species. The trans isomer of ngaione [(-)-epingaione], present in low concentration in some of these essential oils, is formed from ( -)-ngaione during fractional distillation or more rapidly by base-catalysed epimerization. "Isongaione acetate" prepared from (-)-ngaione by treatment with acetic anhydride-sodium acetate is shown to be a mixture of a, β- and β, γ-unsaturated ketones and obtainable in optically active form contrary to literature statements. Oxidation of the optically active β,γ-unsaturated ketone yields (-) acetylmalic acid from which it follows that (-)-ngaione is l(S),4(R)-β-(4,8-dimethyl-6-oxo-1,4-epoxynonyl)furan, ipomeamarone is the 1(R),4(S) enantiomer, and (-)-epingaione is the 1(S),4(S) isomer.