  We have investigated past measurements of the local supermassive black hole
mass density, correcting for hitherto unknown dependencies on the Hubble
constant, which, in some cases, had led to an underestimation of the mass
density by factors of ~2. Correcting for this, we note that the majority of
past studies yield a local supermassive black hole mas density that is
consistent with the range 4.4-5.9 x 10^5 f(H_0) M_Sun / Mpc^3 (when using H_0 =
70 km/s/Mpc). In addition, we address a number of ways in which these past
estimates can be further developed. In particular, we tabulate realistic
bulge-to-total flux ratios which can be used to estimate the luminosity of
bulges and subsequently their central black hole masses.
