Three new pentacyclic aromatic alkaloids, 6-8, have been isolated from two ascidians. The structure of meridine, 6, obtained from Amphicarpa meridiana collected in South Australia, was determined by X-ray analysis while that of a relatively stable tautomer thereof, 7, was established by spectral analysis. The remaining alkaloid, 11-hydroxyascididemin (8), was isolated from a Leptoclinides sp. from Truk Lagoon. All three alkaloids are cytotoxic and one shows slight topoisomerase II activity. Limitations to the possible structures for neocalliactine acetate are discussed.