Earl, as Arkie says, your question about origins is interesting, but I don't know the answer.

In relation to the line in question, Roy Book Binder on 'Live Book ...' introduces the song with an amusing anecdote about Pink Anderson and sings 'Said, "Bill vote across the very top line"'. I think you and Mousethief will agree this is definitely not what Anderson was singing on the Riverside recording. Roy avoids the 'apeyard' puzzle by singing 'graveyard' again.

--Stewie.