From
www.buckeye-web.com/ifmtl3.html
The famous Swan Song symbol that Zeppelin adopted as the logo for
their record label was borrowed from an 1851 oil-on-canvas
painting by William Rimmer entitled "Evening Fall Of Day." The
figure in the painting is the Greek sun god Apollo. The painting
is not, as some people would have you believe, of Icarus or
Daedalus. These two are also figures from Greek mythology.
Daedalus is, according to legend, supposed to have crafted a set
of wings from feathers and wax for himself and Icarus which they
could use to escape from their prison on Crete to freedom in
Greece. Unfortunately, Icarus being the younger of the two
thought it might be a lark to fly a little higher, and flew too
close to the sun which melted his wings and he plunged to his
death in a sea, which is still known as the Icarian sea. Icarus'
first flight was also his swan song. Daedalus also designed the
labyrinth on Crete for King Mino's minotaur, which was the reason
for his imprisonment, because he alone knew the secrets of the
labyrinth.
Look here
www.zepfanman.com/swansong.html for the picture. It's actually called Evening (The Fall of Day).