Prohibitions against eating certain animals?

I sometimes see rules suggesting that monks (at least Theravadan) should not eat various animals. The lists vary, but includes to varying degree: elephants, horses, dogs, snakes, lions, tigers, leopards, bears, hyenas, slugs, cows, and humans. When I try to find something authoritative about this, I've come up short. Can anyone shed light on: (1) is there a list of animals that monks are prohibited from eating, and if so, (2) where does this appear in the canon, and (3) how/why were the particular animals listed?