  The Isgur-Wise functions for the ground state to ground state semileptonic
decays involving $b \rightarrow c$ transitions are calculated from the
(modified) MIT bag model. It is checked that the results for the decays
$\overline{B} \rightarrow D l \overline\nu$ and $\overline{B} \rightarrow D^* l
\overline\nu$ agree well with experiment. Predictions for the decays $\Lambda_b
\rightarrow \Lambda_c l \overline\nu$, $\overline{B}_s \rightarrow D_s l
\overline\nu$ and $\overline{B}_s \rightarrow D^*_s l \overline\nu$ are given
and discussed.
