MAMMALIA
Mammalia, class Mammalia
(noun) warm-blooded vertebrates characterized by mammary glands in the female
Source: WordNet® 3.1
Mam*ma"li*a, n. pl. Etym: [NL., from L. mammalis. See Mammal.]
(Zoöl.)
Definition: 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 threes 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 mammæ.
Source: Webster’s Unabridged Dictionary 1913 Edition