  We present high-resolution, high signal to noise absorption-line observations
of CN, Ca II, Ca I, CH^+, and CH along twenty lines of sight toward members of
the Pleiades. The acquired data enable the most detailed study to date of the
interaction between cluster stars and the surrounding interstellar gas. Total
equivalent widths are consistent with previous investigations except where
weaker features are detected owing to our greater sensitivity. Mean b-values
for the molecular species indicate that toward most of the Pleiades CH is
associated with the production of CH^+ rather than CN. An analysis of radial
velocities reveals a kinematic distinction between ionized atomic gas and
molecular and neutral gas. Molecular components are found with velocities in
the local standard of rest of either ~ +7 km s^-1 or ~ +9.5 km s^-1, with the
higher-velocity components associated with the strongest absorption. Atomic gas
traced by Ca II shows a strong central component at v_LSR ~ +7 km s^-1
exhibiting velocity gradients indicative of cloud-cluster interactions. Gas
density estimates derived from measured CH/CH^+ column density ratios show good
agreement with those inferred from H_2 rotational populations, yielding typical
values of n ~ 50 cm^-3. Our models do not include the important time-dependent
effects on CH^+ formation which may ultimately be needed to extract physical
conditions in these clouds.
