\begin{table}%t3
\caption{Summary of the two observational samples. \label{sum-up} } 
%\centerline
{
 \begin{tabular}{lcc}
   \hline  \hline
   Sample name & FSM & IRAS \\ 
\hline	
   Number of IR sources:&&\\ 
   - initial IR photometric sample&24&38\\	
   - optical identifications and redshifts&26&28\\	 	 
   - with ${\rm H}\alpha$ emission line&23&21\\	  
   \hline
 \end{tabular}}
 \medskip
Comments: three IR  sources (two in the FSM sample and one in 
   the IRAS sample) have been split into two optical objects.
 \end{table}