The Collaborative International Dictionary of English v.0.48:

Chief hare \Chief" hare`\ (Zool.)
   A small rodent (Lagamys princeps) inhabiting the summits of
   the Rocky Mountains; -- also called crying hare, calling
   hare, cony, American pika, and little chief hare.
   [1913 Webster]

   Note: It is not a true hare or rabbit, but belongs to the
         curious family Lagomyid[ae].
         [1913 Webster]