The Collaborative International Dictionary of English v.0.48:

Pika \Pi"ka\, n. (Zool.)
   Any one of several species of tailless rodents of the genus
   Ochotona (formerly Lagomys), resembling small rabbits,
   but with short ears alnd legs. They inhabit the high
   mountains of Asia and America. Called also calling hare,
   and crying hare and rock rabbit. See Chief hare.
   [1913 Webster +PJC]

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]