  This paper presents a study of the Cetus dwarf, an isolated dwarf galaxy
within the Local Group. A matched-filter analysis of the INT/WFC imaging of
this system reveals no evidence for significant tidal debris that could have
been torn from the galaxy, bolstering the hypothesis that Cetus has never
significantly interacted with either the Milky Way or M31. Additionally,
Keck/Deimos spectroscopic observations identify this galaxy as a distinct
kinematic population possessing a systematic velocity of $-87\pm2{\rm km\
s^{-1}}$ and with a velocity dispersion of $17\pm2{\rm km s^{-1}}$; while
tentative, these data also suggest that Cetus possesses a moderate rotational
velocity of $\sim8{\rm km s^{-1}}$. The population is confirmed to be
relatively metal-poor, consistent with ${\rm [Fe/H]\sim-1.9}$, and, assuming
virial equilibrium, implies that the Cetus dwarf galaxy possesses a
$M/L\sim70$. It appears, therefore, that Cetus may represent a primordial dwarf
galaxy, retaining the kinematic and structural properties lost by other members
of the dwarf population of the Local Group in their interactions with the large
galaxies. An analysis of Cetus's orbit through the Local Group indicates that
it is at apocentre; taken in conjunction with the general dwarf population,
this shows the mass of the Local Group to be $\gta2\times10^{12}M_\odot$.
