It was shown by Barger, Martin, and Mitchell that Australian Duboisia myoporoides yielded hyoscine and small amounts of four new alkaloids (tigloidine, valeroidine, poroidine, isoporoidine), with no trace of hyoscyamine. A recent Australian material marketed as "D. myoporoides" was found to contain 4.1% total alkaloids, and the following individual alkaloids were isolated: l-hyoscyamine (1.97%), l-hyoscine (0.06%), dl-hyoscine (0.06%), norhyoscyamine (0.01%), and a new alkaloid provisionally named "Base D" (0.06%). Botanical examination by Dr. Metcalfe of the Royal Botanic Gardens, Kew, considering stomatal distribution on the upper and lower leaf surfaces, indicated that the material previously found to contain no hyoscyamine was authentic D. myoporoides, whereas the present specimen was probably D. Leichhardtii. It is suggested that at least two distinct types of Duboisia, and possibly other intermediate forms, have appeared on the market simply as "Duboisia" or "Duboisia myoporoides", which accounts for the discrepancies between the results of various investigators. The new alkaloid "Base D" (C₁₄H₂₅O₂N) is similar to tigloidine, valeroidine, and the poroidines in that its hydrobromide is very soluble in chloroform. On hydrolysis, it yields tropine and a liquid acid thought to be mainly isovaleric acid. Isovaleryltropeine hydrobromide was synthesised but was not identical with "Base D" hydrobromide. Due to the very small amount of material available, its constitution is not definitely established. It is of interest to note that whereas D. myoporoides yielded minor alkaloids which were esters of +tropine, a dihydroxytropane, and nortropine respectively, D. Leichhardtii has yielded a minor alkaloid which is an ester of tropine, and that except in the case of tigloidine (tiglyl-ψ-tropeine), they were all pentoic acid esters. "Base D" is optically inactive and saturated.