The Collaborative International Dictionary of English v.0.48:

Monodactylous \Mon`o*dac"tyl*ous\, a. [Gr. monoda`ktylos; mo`nos
   single + da`ktylos finger: cf. F. monodactyle.] (Zool.)
   Having but one finger or claw.
   [1913 Webster] Monodelph