Definition of Placentalia. Meaning of Placentalia. Synonyms of Placentalia
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Definition of Placentalia
Placentalia Placentalia Plac`en*ta"li*a, n. pl. [NL.] (Zo["o]l.)
A division of Mammalia including those that have a placenta,
or all the orders above the marsupials.
Placentalia Mammalia Mam*ma"li*a, n. pl. [NL., from L. mammalis. See
Mammal.] (Zo["o]l.)
The highest class of Vertebrata. The young are nourished for
a time by milk, or an analogous fluid, secreted by the
mammary glands of the mother.
Note: Mammalia are divided into three subclasses; -- I.
Placentalia. This subclass embraces all the higher
orders, including man. In these the fetus is attached
to the uterus by a placenta. II. Marsupialia. In
these no placenta is formed, and the young, which are
born at an early state of development, are carried for
a time attached to the teats, and usually protected by
a marsupial pouch. The opossum, kangaroo, wombat, and
koala are examples. III. Monotremata. In this group,
which includes the genera Echidna and
Ornithorhynchus, the female lays large eggs
resembling those of a bird or lizard, and the young,
which are hatched like those of birds, are nourished by
a watery secretion from the imperfectly developed
mamm[ae].
