E. S. Lull — Evolution of the Elephant. 179 



Of the prenatal life of the elephant, covering a period of 

 twenty months, we know very little, but it is reasonable to sup- 

 pose that embryology would give us much more light upon 

 the development of elephantine features. New-born young 

 are elephant-like in every particular with the exception of the 

 skull. 



Paleontology. 



The great proof of the evolution of a race of animals is the 

 finding in the ancient rocks more and more primitive forms as 

 one recedes in time, until the most archaic type is reached. 

 By the study of such a series of fossils not only may the evolu- 

 tionary changes be learned, but former geographical distribu- 

 tions, the original home and the various migrations of the race. 

 While this matter is treated much more fully in the second 

 and third parts of this paper, a brief summary of the racial 

 history may be given as follows : 



The earliest known proboscidians were discovered in the 

 Egyptian Fayum, in beds of middle Eocene age. Their remains 

 are also found in the Upper Eocene of the Fayum, but the 

 Oligocene elephants are as yet undiscovered. During the 

 early Miocene the first migration occurred into Europe and 

 thence to the region of India and even as far as North America, 

 both of which were reached by the Middle Miocene. The 

 Pliocene saw the elephants in their millenium, having reached 

 the widest dispersal and the maximum in numbers of species. 

 During Pleistocene times the Proboscidia covered all of the 

 great land masses except Australia, but were diminishing in 

 numbers, and toward the close of the Pleistocene the period 

 of decadence began, resulting in the extinction of all but the 

 Indian and African elephants of to-day. 



Summary of the Evolution. 



The physical changes undergone by the race are also clearly 

 shown, as the paleontological series is very complete. These 

 changes may thus be summarized : Increase in size and in 

 the development of pillar-like limbs to support the enormous 

 weight. Increase in size and complexity of the teeth and their 

 consequent diminution in numbers and the development of 

 the peculiar method of tooth succession. The loss of the canines 

 and of all of the incisor teeth except the second pair in 

 the upper and lower jaws and the development of these as 

 tusks. The gradual elongation of the symphysis or union of 

 the lower jaws to strengthen and support the lower tusks while 

 digging, culminating in Tetrabelodon angustidens. The appar- 

 ently sudden shortening of this symphysis following the loss 

 of the lower tusks and the compensating increase in size and 

 the change in curvature of those of the upper jaw. 



