  In this paper, we collect radio and X-ray observations for most
Fanaroff-Riley I (FRI) radio galaxies in the Zirbel-Baum radio galaxy sample,
and investigate the distribution of the radio-to-X-ray effective spectral
index, $\alpha_{rx}$, to test the unified scheme of BL Lac objects and FRI
radio galaxies. It is found that the range of $\alpha_{rx}$ for FRI radio
galaxies is almost the same as that for BL Lac objects, that the distribution
of $\alpha_{rx}$ probably peaks at the same position as BL Lac objects, and
that the distribution of $\alpha_{rx}$ for FRIs is similar to that for BL Lac
objects. These suggest that there exist two subclasses of FRI radio galaxies:
one is HBL-like, and the other is LBL-like, corresponding to high-energy-peaked
(HBL) and low--energy-peaked (LBL) BL Lac objects, respectively. This result is
consistent with previous VLA observations, and supports the unified scheme of
BL Lac objects and FRI radio galaxies.
