The Syd Barrett-penned “Scream Thy Last Scream” was supposed to be Pink Floyd’s fourth single (fitting in after “Apples and Oranges” and before “It Would Be Be So Nice”) but the song, and its intended b-side, “Vegetable Man” (about a loser superhero) were never released. Having said that they’ve been heavily bootlegged for years, since acetates (glass test pressings) were cut. In fact, there are several versions (mono, two stereo mixes) known to exist. I can’t believe such amazing songs have never been given legit release on a Pink Floyd or Syd Barrett compilation.
 

 
“Vegetable Man” was memorably covered by the Jesus and Marychain as the b-side to their “Upside Down” single.
 

 
You can download a full complement of these tunes at the great Pathway To Unknown Worlds blog.