Six novel alkaloids, segoline A (1), segoline B (2), isosegoline A (3), norsegoline (4), debromoshermilamine A (5), and eilatin (6), possessing the benzo-1,6-diazaphenanthroline ring system have been isolated from the Red Sea tunicate Eudistoma sp. Eilatin (6) is unusual in having a symmetrical heptacyclic structure. The structures of all compounds were elucidated on the basis of spectroscopic data and, in the cases of compounds 1 and 2, with chemical transformations. The relative configurations of the chiral compounds 1-3 is suggested on the basis of circular dichroism measurements. The structures of four of the compounds (1, 3, 4, and 6) have already been described by us in two short communications. This report describes the structure and spectral features of the two new compounds (2 and 5), the comprehensive spectral data of all the compounds, and the stereochemistry and relative configurations of the three chiral compounds 1-3. The report also includes chemical reactions performed on compounds 1 and 2.