  We consider models of gas flow in spiral galaxies in which the spiral
structure has been excited by various possible mechanisms: a global steady
density wave, self-gravity of the stellar disc and an external tidal
interaction, as well as the case of a galaxy with a central rotating bar. In
each model we estimate in a simple manner the likely current positions of star
clusters of a variety of ages, ranging from ~ 2 Myr to around 130 Myr,
depending on the model. We find that the spatial distribution of cluster of
different ages varies markedly depending on the model, and propose that
observations of the locations of age-dated stellar clusters is a possible
discriminant between excitation mechanisms for spiral structure in an
individual galaxy.
