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76 perfectly the peculiarities of both these orders. It must be mentioned, however, that Haeckel considers the whales, etc. as being more nearly allied to the Sea-cow, etc. With the exception of the Ant-eater of South Africa and the Pangolin common to Asia and Africa, the Edentata, so called from many of them having no front or incisor teeth, and some no teeth at all, are confined to South America, represented there by the Sloths, Armadillos, and Ant-eaters. The Sloths differ from all other Mammalia in having more than seven bony pieces in the neck, there being nine cervical vertebrae in the three-toed Sloth, and in the great number of ribs (twenty-three) in the two-toed Sloth, as well as in the bird-reptile arrangement of the viscera, agreeing in this peculiarity with the Ornithorhynchus; in many other respects the Edentata show a low grade of organization. From the wide geographical distribution, the gradual extinction, and the reptile-bird-like organization of the Edentata, we consider them as the survivors of an order which must have diverged very early from the main stem of the Mammalia. Gigantic fossils belonging to this order, like the Megatherium, Megalonyx, Mylodon, have been found in remote parts of the earth, showing the extent and size of the order in past time. The Megatherium (twenty-two feet in length) combines the head of the Sloth with the backbone and extremities of the Ant-eater. In the present state of Paleontology and Embryology, it is impossible to indicate the progenitors of these extinct Edentates.

With the Edentata we leave the Mammalia, and, for the present, the structure of the animal kingdom. We have endeavored to show—following principally Haeckel—that there is a main trunk of life, beginning in the Monads, ending in Man; here and there large branches are given off, terminating in twigs and leaflets. Allusions have been made to extinct animals, often forming an essential part of these branches. The relation, in time, that these extinct