EVOLUTION OF THE ELEPHANT LULL. 665 



more like those of other mammals. The grinding teeth are extremely- 

 simple, the premolars having 3 while the molars have but 2 

 cross crests with open, luicemented valleys. Tusks are apparently 

 confined to the lower jaw, no trace of ujDper tusks having been seen 

 in the only known skull, now unfortunately lost. Those of the lower 

 jaw were large and, together with the elongated symphysis, bent 

 abruptly downward, the tips being actually recurved. The skeleton, 

 so far as known, indicates a huge elephant-like body and limbs and 

 the impression is that the creature must have been semiaquatic, fre- 

 quenting the beds of streams and living upon the succulent herbage 

 which it rooted up by means of its tusks. The contour of the skull is 

 ill known, so that, with the exception of the lower jaw, restorations 

 of the head are largely conjectural. Dlnotherium died out in the 

 Pliocene, leaving no descendants. 



Part III. 



MIGRATIONS OF THE PROBOSCIDEA. 



In studying the dispersal of a group of terrestrial vertebrates one 

 has to consider not alone the probability of land bridges over which 

 the wandering hordes might pass, but, on the other hand, the existence 

 of barriers to migration other than the absence of these bridges. 



The possible barriers are climatic, topographic, and vegetative. 

 Of these the climatic has been given weight, but in the case of the 

 proboscidians the direct action of temperature is relatively unim- 

 portant, though the jDresence of moisture is a prime necessity. 



The African elephant formerly ranged from Cape of Good Hope 

 into Spain, while Elephas primigenms enjoyed an even greater range 

 in latitude and consequent temperature. The African species has a 

 vertical distribution from sea level to a height of 13,000 feet in the 

 Kihmanjaro region, which also gives a great range of climatic varia- 

 tion. Aridity, however, is a most efficient barrier, not only from its 

 effect upon the food supply, but because water is a prime necessity 

 to elephantine comfort. The Sahara to-day marks the northernmost 

 limit of the African species, the former distribution to the north 

 being by way of the Nile Valley or possibly to the w^estward of the 

 Great Desert. 



Mountain ranges on the whole do not impede elephant migration, 

 except of course such mighty uplifts as the Himalayas. The height 

 to Avhich the elephant wanders in the Kilimanjaro has already been 

 mentioned, while Hannibal took a number of African elephants 

 across the Little St. Bernard pass, which has an altitude of 7,176 

 feet, in his invasion of Italy in 218 B. C. The Pyrenees, however, 

 seem to have prevented the numerous elephants of France from in- 



