yapack

from The Collaborative International Dictionary of English v.0.48

Yapock \Ya"pock\ (?; 277), n. [Probably from the river Oyapok,
   between French Guiana and Brazil.] (Zool.)
   A South American aquatic opossum ({Chironectes variegatus})
   found in Guiana and Brazil. Its hind feet are webbed, and its
   fore feet do not have an opposable thumb for climbing. Called
   also {water opossum}. [Written also {yapack}.]
   [1913 Webster]
   [1913 Webster]