In Season 8, Episode 9 of Futurama, called "Fry Am the Egg Man", Leela says that she has 205 bones in her body. A normal human has 206 (at adulthood), so what bone is Leela missing?
We can see from the image below (from season 6) that Leela's skeleton is completely normal from the neck down. That would strongly imply that the bone that she's missing is within her skull or upper neck.
Presumably she's missing her nasal bone, since that would conflict with her big centrally-located eye.