  In this paper we construct some packets of representations which have to
correspond to relatively general Arthurs packets; this is for any classical
group $G$ over a p-adic field $F$. An Arthur's packet correspond to a map
$\psi$ from $W_{F} \times SL(2,{\mathbb C}) \times SL(2,{\mathbb C})$ into the
$L$-group of $G$. The packets we consider here have the property that the
centralizer of $\psi$ in the dual group is a finite groupe. Our construction is
a combinatorial one which reduce the study of the representations in such a
packet to tempered representation of eventualy smaller groups; in fact we give
a precise description of the representations associated to $\psi$ and a
character of the centralizer of $\psi$ in the L-group in the Grothendieck
group. Stability properties follow easily from analogous properties for the
tempered packet which enter the situation.
