Bookworm is correct.
Mathematically, lateral stability is the partial derivative of rolling moment with respect to sideslip. Directional stability is similarly the partial derivative of yawing moment with sideslip.
The spiral mode (aerodynamically at-least) is largely down the ratio of the two. If lat / dir is greater than 1.0, then the spiral stability should be positive.
Dutch Roll excitement is down to the lateral and directional damping. The damping, and the actual stability values are not closely related.
The ratio of the DR is roughly the same as the ratio of the stabilities. So, if the wingtip describes a circle during DR, expect roughly neutral spiral-stab. Alternatively, if the wingtip describes a flat oval with it's axis parallel to the horizon, expect it to be spirally divergent, because this indicates that directional stability is greater than lateral.
G