The Collaborative International Dictionary of English v.0.48:

Gerboa \Ger*bo"a\, n. (Zool.)
   The jerboa.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Jerboa \Jer*bo"a\, n. [Ar. yarb[=u]`.] (Zool.)
   Any small jumping rodent of the genus Dipus, esp. Dipus
   Aegyptius, which is common in Egypt and the adjacent
   countries. The jerboas have very long hind legs and a long
   tail. [Written also gerboa.]
   [1913 Webster]

   Note: The name is also applied to other small jumping
         rodents, as the Pedetes Caffer, of the Cape of Good
         Hope.
         [1913 Webster]

   Jerboa kangaroo (Zool.), small Australian kangaroo
      (Bettongia penicillata), about the size of a common
      hare.
      [1913 Webster]