Ruby doesn't have meta classes
So what is a meta class then? Well, it's a class that defines the behavior of other classes. You can define meta classes in Ruby if you want too by defining a subclass of Class. Those classes would be metaclasses.
Edit: Of course, if you actually try to define a subclass of Class you will find that Ruby doesn't allow you to do that, which means that you don't have any meta classes in Ruby. Period.