The Collaborative International Dictionary of English v.0.48:

macrotus \ma*cro"tus\, n.
   A large-eared grayish bat (Macrotus californicus) of
   southern California and northwestern Mexico.
   [WordNet 1.5] Macroura

WordNet (r) 3.0 (2006):

macrotus
    n 1: large-eared greyish bat of southern California and
         northwestern Mexico [syn: macrotus, Macrotus
         californicus]