Lagamys princeps

from 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]