The Collaborative International Dictionary of English v.0.48:

Tahr \Tahr\, n. (Zool.)
   Same as Thar.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Thar \Thar\, n. (Zool.)
   A goatlike animal (Capra Jemlaica) native of the Himalayas.
   It has small, flattened horns, curved directly backward. The
   hair of the neck, shoulders, and chest of the male is very
   long, reaching to the knees. Called also serow, and imo.
   [Written also thaar, and tahr.]
   [1913 Webster]