Let f(x) = f(x1, . . . , x8) be an octonary cubic form with rational integral coefficients and nonzero discriminant. Then, on the assumption of a certain type of Riemann hypothesis, we showed in the first paper with the above title that the indeterminate equation f(l)=0 has a non-zero solution provided that f(x) conform to the (necessary) condition that it have a non-trivial zero in every p-ad…