The ascidian Clavelina cylindrica, which was collected in Tasmania, has yielded two novel alkaloids, cylindricine A, rel-(3R, 4R, 5S, 7aR, 11aR)-3-chloromethyl-5-hexyl-perhydro-pyrrolo-[2,1-j]quinolin-7-one, (12), and cylindricine B, rel-(3S, 5R,6S,8aR,12aR)-3-chloro-6-hexyl-perhydropyrido[2,1-j]quinoline-8-one, (13). Cylindricine B is the first example of the new pyrido-[2,1-j]-quinoline ring system while cylindricine A is the first pyrrolo[2, 1-j]quinoline known from nature. Single crystal X-ray studies support the assignment of the two alkaloids. © 1993.