| Implacentalia | ‖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 ] |
| Placentalia | ‖n. pl. [ NL. ] (Zool.) A division of Mammalia including those that have a placenta, or all the orders above the marsupials. [ 1913 Webster ] |