'Implacentalia' definitions:
Definition of 'Implacentalia'
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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]
