  TIGER integral-field spectrography and HST/WFPC2 imaging of the E3 galaxy NGC
2974 are used to derive the kinematics of the stellar and ionized gas
components in its central 500 pc. We derive a numerical two-integral
distribution function from a MGE mass model using the HQ formalism. The TIGER
as well as published long-slit stellar kinematics are well fitted with this
self-consistent model, requiring neither the addition of a significant mass
contribution from a hidden disc structure, nor the presence of a central dark
mass. The data reveal the presence of a striking, highly contrasted, two-arm
gaseous spiral structure within a radius of ~200 pc, corresponding to a total
mass of 6.8x10^4 Msun of ionized gas. We use a deconvolved TIGER datacube to
probe its kinematics at a resolution of about 0.35 arcsec. Strong departures
from circular motions are observed, as well as high velocity dispersion values
on the inner side of the arms. We interpret the observed gas morphology and
kinematics as the signature of streaming gas flows driven by a ~540 pc diameter
bar with Ome=700+/-100 km/s/kpc. This hypothesis is strongly supported by the
predictions of a density wave model. This model predicts that the bar should
lie at about 35 degree from the line of nodes, and implies gas inflow towards
the central ~50 pc. The quadrupole pertubation due to this bar is estimated to
represent less than 2% of the underlying gravitational potential. Despite its
weakness, the inner bar of NGC 2974 may be able to drive some gas within a 10
pc radius. We suggest that the presence of such inner bars might be more common
among early-type disk galaxies than is generally thought, and that deep
high-resolution emission-line imagery may be the best way to detect such
structures.
