"I can't let an eel in the library," William responded, thoroughly distracted now. "Or a bird. Or a slug."
The 'banned Patronus' list in his head was rapidly reaching epic proportions, and he hadn't even seen what the rest of the school was carting around right now. "Do you think we should call an emergency meeting?" he asked worriedly. "To figure out what to do?" And how to make the local fauna go away?