How to tell if something is an IEnumerable<>?

I've got a Type.

How can I tell if it's an IEnumerable<>?

These:

   typeof(IEnumerable<>).IsAssignableFrom(memberType);
   typeof(IEnumerable<object>).IsAssignableFrom(memberType);

return false for IEnumerable<int>

Whereas this:

   typeof(IEnumerable).IsAssignableFrom(memberType);

returns true for string.