  This paper presents an analysis of the correlation between the number of
globular clusters (N_GC) in giant galaxies and the mass of the galaxies'
central supermassive black hole (M_SMBH). I construct a sample of 20
elliptical, spiral, and S0 galaxies with known SMBH masses and with
accurately-measured globular cluster system properties derived from wide-field
imaging studies. The coefficients of the best-fitting N_GC-M_SMBH relation for
the early-type galaxies are consistent with those from previous work but in
some cases have smaller relative errors. I examine the correlation between N_GC
and M_SMBH for various subsamples and find that elliptical galaxies show the
strongest correlation while S0 and pseudobulge galaxies exhibit increased
scatter. I also compare the quality of the fit of the numbers of metal-poor
globular clusters versus SMBH mass and the corresponding fit for metal-rich
globular clusters. I supplement the 20-galaxy sample with ten additional
galaxies with reliable N_GC determinations but without measured M_SMBH. I use
this larger sample to investigate correlations between N_GC and host galaxy
properties like total galaxy luminosity and stellar mass and bulge luminosity
and mass. I find that the tightest correlation is between N_GC and total galaxy
stellar mass. This lends support to the notion that N_GC and M_SMBH are not
directly linked but are correlated because both quantities depend on the host
galaxy potential. Finally, I use the N_GC-M_SMBH relation derived from the
20-galaxy sample to calculate predicted M_SMBH values for the ten galaxies with
accurate N_GC measurements but without measured SMBH masses.
