  The 21cm line emission from a 7x6 degree region, east of and adjoining the
Small Magellanic Cloud (SMC) has been observed with the Australia Telescope
Compact Array and the Parkes telescopes. This region represents the westernmost
part of the Magellanic Bridge, a gas-rich tail extending ~14 degrees to the
Large Magellanic Cloud (LMC). A rich and complex neutral hydrogen (HI)
structure containing shells, bubbles and filaments is revealed. On the larger
scale, the HI of the Bridge is organised into two velocity components. This
bimodality, which appears to originate in the SMC, converges to a single
velocity component within the observed region. A census of shell-like
structures suggests a shell population with characteristics similar to that of
the SMC. The mean kinematic age of the shells is ~6 Myr, in agreement with the
SMC shell population, but not with ages of OB clusters populating the
Magellanic Bridge, which are approximately an factor of three older. In
general, the projected spatial correlation of Bridge HI shells with OB
associations is poor and as such, there does not appear to be a convincing
relationship between the positions of OB associations and that of expanding
spherical HI structures. This survey has found only one HI shell that has an
identifiable association with a known Ha shell. The origin of the expanding
structures is therefore generally still uncertain, although current theories
regarding their formation include gravitational and pressure instabilities, HVC
collisions and ram pressure effects.
