76 EVOLUTION OF LIFE. 
perfectly the peculiarities of both these orders. It must 
be mentioned, however, that Haeckel considers the whales, 
etc. as being more مت‎ 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 cer- 
vical 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 organi- 
zation. From the wide geographical distribution, the grad- 
ual 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 
ofthe 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 
