  We present the first dynamical analysis of a galaxy cluster to include a
large fraction of dwarf galaxies. Our sample of 108 Fornax Cluster members
measured with the UK Schmidt Telescope FLAIR-II spectrograph contains 55 dwarf
galaxies (15.5>bj>18.0 or -16>Mb>-13.5). Halpha emission shows that 36+/-8 per
cent of the dwarfs are star-forming, twice the fraction implied by
morphological classifications. The total sample has a mean velocity of
1493+/-36 km/s and a velocity dispersion of 374+/-26 km/s. The dwarf galaxies
form a distinct population: their velocity dispersion (429+/-41 km/s) is larger
than that of the giants (308+/-30 km/s) at the 98 per cent confidence level.
This suggests that the dwarf population is dominated by infalling objects
whereas the giants are virialized.
  The Fornax system has two components; the main Fornax Cluster centered on NGC
1399 with mean velocity 1478 km/s and velocity dispersion 370 km/s, and a
subcluster centered 3 degrees to the south-west including NGC 1316 with mean
velocity 1583 km/s and velocity dispersion 377 km/s. This partition is
preferred over a single cluster at the 99 per cent confidence level. The
subcluster, a site of intense star formation, is bound to Fornax and probably
infalling towards the cluster core for the first time. We discuss the
implications of this substructure for distance estimates of the Fornax Cluster.
