\begin{table}%t1
\caption{Mean redshifts and velocity dispersions for A3667.\label{tab:prevopt}}
%\centerline
 {\begin{tabular}{lcll}
\hline\hline
\noalign{\smallskip}
Reference & $N$     & Mean $z$    &$\sigma_{\rm v}$ (km~s$^{-1}$) \\
\noalign{\smallskip}
\hline
\citet{Proust88} & 46$^{{\rm *}}$  & 0.054~$\pm$~0.003 & 1606~$\pm$~288\\
\citet{Sodre92}  & 120 & 0.0553~$\pm$~0.0004 & 1197~$\pm$~79\\
\citet{Girardi96}& 123 &        & $\rm 1208 ^{+95}_{-84}$\\
\citet{Girardi98}& 154 & 0.0566 & $\rm 971^{+62}_{-47}$\\
This paper& 231 & 0.0555~$\pm$~0.0003\rlap{$^{\ddagger}$} & 1102~$\pm$~46\\[1mm]
\hline
\end{tabular}}
\par
\smallskip
$^{{\rm *}}$ From the table in \citet{Proust88}.
$^{\ddagger}$ The mean of all 231 available redshifts; the best-fit Gaussian to
the data gives $\overline{z}=0.0553$ (see Sect.~6).
\end{table}