Implacentalia

1 definition found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Implacentalia \Im`pla*cen*ta"li*a\, n. pl. [NL. See {In-} not,
     and {Placental}.] (Zool.)
     A primary division of the Mammalia, including the monotremes
     and marsupials, in which no placenta is formed.
     [1913 Webster]