  The in-plane Hall coefficient $R_{H}(T)$ of CeRhIn$_{5}$, CeIrIn$_{5}$, and
CeCoIn$_{5}$ and their respective non-magnetic lanthanum analogs are reported
in fields to 90 kOe and at temperatures from 2 K to 325 K. $R_{H}(T)$ is
negative, field-independent, and dominated by skew-scattering above $\sim$ 50 K
in the Ce compounds. $R_{H}(H \to 0)$ becomes increasingly negative below 50 K
and varies with temperature in a manner that is inconsistent with skew
scattering. Field-dependent measurements show that the low-T anomaly is
strongly suppressed when the applied field is increased to 90 kOe. Measurements
on LaRhIn$_{5}$, LaIrIn$_{5}$, and LaCoIn$_{5}$ indicate that the same
anomalous temperature dependence is present in the Hall coefficient of these
non-magnetic analogs, albeit with a reduced amplitude and no field dependence.
Hall angle ($\theta_{H}$) measurements find that the ratio
$\rho_{xx}/\rho_{xy}=\cot(\theta_{H})$ varies as $T^{2}$ below 20 K for all
three Ce-115 compounds. The Hall angle of the La-115 compounds follow this
T-dependence as well. These data suggest that the electronic-structure
contribution dominates the Hall effect in the 115 compounds, with $f$-electron
and Kondo interactions acting to magnify the influence of the underlying
complex band structure. This is in stark contrast to the situation in most $4f$
and $5f$ heavy-fermion compounds where the normal carrier contribution to the
Hall effect provides only a small, T-independent background to $R_{H}.$
