Dan Mazur (danmazur) says: I think you're mistaken: the Y isn't missing, it works as the center of the palindrome "subway aw bus," which reads the same backwards and forwards, right? Some palindromes have a double letter at the center ("ed a rap parade" has two "p's"), and others have a single letter, a sort of pivot or fulcrum, like this one. What's confusing, I guess is that it seems like I'm saying "subway" is "aw bus" spelled backwards -- in which case the "y" would be missing. But that's not the palindrome. There, I think I've made that sufficiently confusing and I'll shut up now.