why is :else not (else) in clojure?

In Clojure you can write:

(cond (= 1 2) 1 
      :else 5)

In Scheme the equivalent would be:

(cond ((= 1 2) 1)
       (else 5))

The :else 5 syntax is not as consistent as the (else 5). What is the reason the else syntax is implemented in this seemingly inconsistent way in Clojure?