EVOLUTION OF THE ELEPHANT LULL. 667 



Mammut americanum phylum. 



[See chart 1.] 



Tetrdbelodon angustidens did not go unaccompanied, for another 

 type, Tetraljelodon turicensis { = tapiroides), found in the Lower 

 Miocene of Algeria, must have traveled into Europe by the same route 

 and about the same time. In T. turicensis the grinders are simple in 

 character, as though it had already begun to differ in its feeding 

 habits from its contemporary, in which the teeth are comparatively 

 complex. Tetrdbelodon turicensis spread during the Miocene over 

 France, Germany, Austria-Hungary, Russia, and as far as south- 

 eastern Siberia. The successor of Tetrahelodon turicensis was Mam- 

 mut horsoiii, covering much the same geographical area as its fore- 

 bear, being found as far as England to the north and Russia, along 

 the northern coast of the Black Sea, to the east. Geologically it 

 ranges from Lower to Upper Pliocene. 31. borsoni merges into 

 Mammut americanum., the great American mastodon, which outlived 

 the mammoth in the new world. Some teeth found in southeastern 

 Russia have been referred to the American type by Madame Pavlow, 

 who was perfectly familiar with M. borsoni. However that may be, 

 the migration of this race was without doubt across Siberia, the 

 Behring isthmus and into the new world from the northwest. The 

 American mastadon's remains have been found from Alaska to Cali- 

 fornia, east to Prince Edwards Island, and from Hudson Bay to 

 Florida on the east coast, while Le Conte reports a specimen from 

 Tambla, Honduras, about 15° north latitude, the nearest recorded 

 approach to South America. 



Tetrabelodon, Dibelodon phylum; Tetrabelodon, Elephas phylum. 



[See chart 2.] 



Reverting once more to T etixibelodon angustidens., we find in it the 

 possible ancestor of all of the later proboscidians, with the exception 

 of the very aberrant Dinotheres and the American mastodon phylum. 

 Tetrdbelodon angustidens was a great migrant, covering most of 

 Europe with the exception of Spain and England. Its descendants 

 diverged along several lines of specialization, as along varied lines of 

 travel, at least one representative reaching North America in the 

 Middle Miocene (Deep River beds), possibly before (Virgin Valley 

 of Oregon, Merriam)." The earliest North American form, Tetra- 

 belodon productus., resembled its European prototype very closely 

 and gave rise to a remarkable group of four-tusked mastodons which 

 ranged from Nebraska to Florida. From some of the later species 

 arose the Dibelodon race with upper, enamel-banded tusks, but lack- 



"A still earlier type, Gomphnthcrium (-Tetrahelodon) conodon Cook, has just 

 been described from the lower Miocene (upper Harrison) beds of western 

 Nebraska. 



