  We present a 3D kinematical analysis of stars located in Kapteyn Selected
Area 71 (l = 167.1, b = -34.7), where previously a stellar excess was found
(Dinescu et al. 2002, Newberg et al. 2002). Previous findings indicated that
the stellar excess has a cold kinematical signature as inferred from proper
motions, and was initially associated with debris from the Sagittarius dwarf
galaxy (Sgr) -- namely the southern trailing tail. We have obtained radial
velocities using the Hydra multiobject spectrograph on the WIYN 3.5 m
telescope. Results for 183 proper-motion selected stars indicate that the
dominant population in this stellar excess is not debris from Sgr, but rather a
population that kinematically belongs to the ring-like stream that is now known
as the Monoceros stream. The orbit determined for this population agrees very
well with the predictions for the Monoceros stream from Penarrubia et al.
(2005). The radial-velocity dispersion of this population is between 20 and 30
km/s, lower than that of the Galactic field. Also, the shape of the
radial-velocity distribution shows a sharp cut-off on one side, which is more
in line with model predictions of the disruption of a satellite rather than
with the distribution of the Galactic field. Despite the fact that we now
believe most of the stars in the stellar excess to be part of Monoceros, about
ten stars in this stellar excess have highly negative radial velocities, which
is a clear indication of their membership to the Sgr trailing tidal tail.
