typical velocities $V\sim1-10$ kms$^{-1}$ at separation scales from 40 to 200 pc. The velocity of star formation propagation falls more steeply with time and distance in peculiar galaxies NGC 3726 and NGC 5585 at all studied ranges of $S$. The exception is the inner range 40-200 pc in NGC 3726. As we noted above, this result is unreliable due to a small number of close SC-H[ii]{}R pairs in the galaxy. Nevertheless, typical velocities $V$ in NGC 3726 and NGC 5585 are also close to a few kms$^{-1}$ as in three galaxies with regular structure.

Variations of $V$ and $\alpha$ for different ranges of $S$ and different morphology of galaxies will be discussed in the next section.

Discussion
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@whitmore2011 studied young star clusters in the grand-design galaxy M83 using the morphology of the surrounding H$\alpha$ emission. The relation between the age of a star cluster and radius of H$\alpha$ bubble, found in @whitmore2011, showed a strong age-size correlation for star clusters younger than $\log (t/{\rm yr})=6.7-6.8$, with ionized gas bubble growing from a few to $\approx20$ pc in size. There is no age-size correlation for star clusters older than $\log (t/{\rm yr})=6.8$ and bubble’s radius $>20$ pc. At this distance, 