188 



It. S. Lull — Evolution of the Elephant. 



downwardly projecting-, while the lower ones were directed 

 forward, their combined upper surface forming a continuation 

 of the spout-like union or symphysis of the jaws. The molar 

 teeth, 2± in number, bore on the crown four 

 low tubercles partially united into two trans- 

 verse crests. The neck was of sufficient length 

 to enable the animal readily to reach the 

 ground, though the prehensile lip must have 

 been used for food-gathering. Our knowl- 

 edge of the creature's bodily form is imper- 

 fect, as a complete skeleton has not been 

 found. Mceritherium, measured about 3^ feet 

 in height, and existed up into the Upper Eocene as a contem- 

 porary of Pal&omastodon, doubtless owing to a continuation 

 of those favorable conditions under which it lived. 



Fig. 13. Tooth of 

 Mceritherium ( x \), 



Palceomastodon. 



JPalceornastodon of the Upper Eocene was more elephant- 

 like than its predecessor, Mceritherium,, and of larger size, 

 while its limbs were much like those of more modern types. 

 The skull has increased materially in height, with a consider- 



Fig. 14. Skull of Palasornastodon ( x J 3 ) ; after Andrews. 



able development of air cells in the bones. The small nasals 

 with the nasal openings had receded so that they lay just in 

 front of the orbits, much as in the tapir of to-day. This would 

 imply the development of a short extensile proboscis, essen- 

 tially like that of the modern elephant except for size. The 

 upper and lower canines and incisors have entirely disappeared 

 except the second pair of incisors in each jaw, whichJiave be- 

 come well-developed tusks. Those of the upper jaw are large, 

 downwardly curved, and with a band of enamel on the outer 

 face. The lower jaw has elongated considerably, especially at 



