  Decompositions of the rotation curves of NGC2613, 3198, 6505, and 7184 are
analysed. For these galaxies the radial velocity dispersions of the stars have
been measured and their morphology is clearly discernible. If the parameters of
the decompositions are chosen according to the `maximum' disk hypothesis, the
Toomre Q stability parameter is systematically less than one and the
multiplicities of the spiral arms as expected from density wave theory are
inconsitent with the observed morphologies of the galaxies. The apparent Q<1
instability, in particular, is a strong argument against the `maximum' disk
hypothesis.
