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Placentalia
(gcide) | Placentalia \Plac`en*ta"li*a\, n. pl. [NL.] (Zool.)
A division of Mammalia including those that have a placenta,
or all the orders above the marsupials.
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Placentalia
(gcide) | Mammalia \Mam*ma"li*a\, n. pl. [NL., from L. mammalis. See
Mammal.] (Zool.)
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.
[1913 Webster]
Note: Mammalia are divided into three subclasses;
[1913 Webster] I. Placentalia. This subclass embraces
all the higher orders, including man. In these the
fetus is attached to the uterus by a placenta.
[1913 Webster] 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.
[1913 Webster] 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 mammae.
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| | podobné slovo | definícia |
Implacentalia
(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.
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