CHAPTER XXL 
PEDIGREE AND HISTORY OF THE ANIMAL KINGDOM. 
IV. MAMMALS. 
The System of Mammals according to Linneus and Blainville—Three 
Sub-classes of Mammals (Ornithodelphia, Didelphia, Monodelphia).— 
Ornithodelphia, or Monotrema.—Beaked Animals (Ornithostoma).— 
Didelphia, or Marsupials.—Herbivorous and Carnivorous Marsupials.— 
Monodelphia, or Placentalia (Placental Animals).—Meaning of the 
Placenta.—Tuft Placentalia.—Girdle Placentalia.—Dise Placentalia.— 
Non-deciduates, or Indeciduata.—Hoofed Animals.—Single and Double- 
hoofed Animals.—Whales.—Toothless Animals.— Deciduates, or Animals 
with Decidua.—Semi-apes.—Gnawing Animals.—Pseudo-hoofed Ani- 
mals.—Insectivora.— Beasts of Prey.—Bats.—Apes. 
THERE are only a few points in the classification of 
organisms upon which naturalists have always agreed. 
One of these few undisputed points is the privileged 
position of the class of Mammals at the head of the animal 
kingdom. The reason of this privilege consists partly 
in the special interest, also in the various uses and the 
many pleasures, which Mammals, more than all other 
animals, offer to man, and partly in the circumstance 
that man himself is a member of this class. For however 
differently in other respects man’s position in nature and 
in the system of animals may have been regarded, yet no 
naturalist has ever doubted that man, at least from a purely 
