Myrionine (1), a new 8beta-alkyl-cis-decahydroquinoline, was isolated from Myrioneuron nutans. Its structure was determined by spectral methods and then confirmed by X-ray analysis and total synthesis. In solution, 1 gives rise to an N-in/N-out equilibrium. The solvent has weak influence on the N-in/N-out ratio for myrionine (1), whereas together with the anions, it plays an important role for myrionine hydrochloride (9) and hydroiodide (10). The two N-in and N-out conformations obtained separately by crystallization of 9 and 10, respectively, were analyzed by X-ray diffraction.