The Collaborative International Dictionary of English v.0.48:

Lagostomus \Lagostomus\ prop. n.
   A mammal genus comprising the viscachas.

   Syn: genus Lagostomus.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Lagostomus
    n 1: viscachas [syn: Lagostomus, genus Lagostomus]