  We study the relationship between the H{\sc i} specific angular momentum
(j$_{\rm g}$) and the H{\sc i} mass (M$_{\rm g}$) for a sample of galaxies with
well measured H{\sc i} rotation curves. We find that the relation is well
described by an unbroken power law \jg $\propto$ \mg$^{\alpha}$ over the entire
mass range (10$^{7}$-10$^{10.5}$ M$_{\odot}$), with $\alpha = 0.89 \pm 0.05$
(scatter 0.18 dex). This is in reasonable agreement with models which assume
that evolutionary processes maintain H{\sc i} disks in a marginally stable
state. The slope we observe is also significantly different from both the $j
\propto M^{2/3}$ relation expected for dark matter haloes from tidal torquing
models and the observed slope of the specific angular momentum-mass relation
for the stellar component of disk galaxies. Our sample includes two H{\sc
i}-bearing ultra diffuse galaxies, and we find that their angular momentum
follows the same relation as other galaxies. The only discrepant galaxies in
our sample are early-type galaxies with large rotating H{\sc i} disks which are
found to have significantly higher angular momentum than expected from the
power law relation. The H{\sc i} disks of all these early-type galaxies are
misaligned or counter-rotating with respect to the stellar disks, consistent
with the gas being recently accreted. We speculate that late stage wet mergers,
as well as cold flows play a dominant role in determining the kinematics of the
baryonic component of galaxies as suggested by recent numerical simulations.
