  Kn-band imaging of a sample of 30 edge-on spiral galaxies with a boxy or
peanut-shaped (B/PS) bulge is discussed. Galaxies with a B/PS bulge tend to
have a more complex morphology than galaxies with other bulge types,
unsharp-masked images revealing structures that trace the major orbit families
of three-dimensional bars. Their surface brightness profiles are also more
complex, typically containing 3 or more clearly separated regions, including a
shallow or flat intermediate region (Freeman Type II profiles), suggestive of
bar-driven transfer of angular momentum and radial redistribution of material.
The data also suggest abrupt variations of the discs' scaleheights, as expected
from the vertical resonances and instabilities present in barred discs but
contrary to conventional wisdom. Counter to the standard `bulge + disc' model,
we thus propose that galaxies with a B/PS bulge are composed of a thin
concentrated disc (a disc-like bulge) contained within a partially thick bar
(the B/PS bulge), itself contained within a thin outer disc. The inner disc
most likely formed through bar-driven processes while the thick bar arises from
buckling instabilities. Both are strongly coupled dynamically and are formed
mostly of the same (disc) material.
