  We study certain physical observables of isoscalar heavy baryons using
potential models based on hadronic degrees of freedom. The goal is to compare
these results with those from an effective theory obtained in a combined heavy
quark and large $N_{c}$ expansion and thereby test the convergence of the
effective theory. We study the excitation energy of $\Lambda_{b}$ and
semileptonic decay form factors. The models tend to confirm the usefulness of
the effective theory for most observables.
