A circular linked list can have only one reference direction (as the linked list) or a double reference as the doubly linked list. The only difference between the circular linked list and a linked list is that the last element's next (tail.next) pointer does not make a reference to null, but to the first element (head), as we can see in the following diagram:

And a doubly circular linked list has tail.next pointing to the head element and head.prev pointing to the tail element: