\begin{table}%t6
%\centering
\par
\caption{Number of spectroscopic members ($N_{\rm g}$), value of the
  $\Delta$ statistic, and the measure of substructuring significance
  $P$, for each of the clusters used in the present analysis (see text
  for details).} \label{tab:DS}
 \begin{tabular}{llll}
 \hline \hline Cluster name & $N_{\rm
  g}$ & $\Delta$ & $P$ \\ \hline Cl~1040 & $30$ & $55.11$ & $0.08$ \\
  Cl~1054--11 & $48$ & $71.77$ & $0.64$ \\ Cl~1054--12 & $36$ &
  $108.87$ & $0.14$ \\ Cl~1216 & $67$ & $135.58$ & $0.05$ \\ Cl~1232
  & $54$ & $96.57$ & $0.01$ \\ \hline \end{tabular} 
  \end{table}