ilO FOSSIL HORSES' TEETH. 



Prof. Thomas H. Huxley says (" Critiques and Ad- 

 dresses," pp. 191-5) : 



u Let us endeavor to find some cases of true linear 

 types, or forms which are intermediate between others, 

 because they stand in a direct genetic relation to them. 

 It is no easy matter to find clear and unmistakable 

 evidence of filiation among fossil animals. After much 



was a horse's tooth hidden in the matrix ; nor was it then known 

 with certainty that the remains of horses were common in North 

 America. Mr. Lyell has lately brought from the United States 

 a tooth of a horse ; and it is an interesting fact that Prof. Owen 

 could find in no species, either fossil or recent, a slight but pecu- 

 liar curvature characterizing it, until he thought of comparing 

 it with my specimen found here. Certainly it is a marvelous 

 fact in the history of the Mammalia, that in South America a 

 native horse should have lived and disappeared, to be succeeded 

 in after ages by the countless herds descended from the few in- 

 troduced by the Spanish colonists ! (I need hardly state here 

 that there is good evidence against any horse living in America 

 at the time of Columbus). 



" When America, and especially North America, possessed its 

 elephants, mastodons, horse, and hollow-horned ruminants, it 

 was much more closely related in its zoological characters to the 

 temperate parts of Europe and Asia than it now is. As the 

 remains of these genera are found on both sides of Behring's 

 Straits and on the plains of Siberia, we are led to look to the 

 northwestern side of North America as the former point of com- 

 munication between the Old and the so-called New World. And 

 as so many species, both living and extinct, of these same genera 

 inhabit and have inhabited the Old World, it seems most prob- 

 able that the North American elephants, mastodons, horse, and 

 hollow-horned ruminants migrated on land since submerged 

 near Behring's Straits from Siberia into North America, and 

 thence on land since submerged in the West Indies into 

 South America, where for a time they mingled with the forms 

 characteristic of that southern continent, and have since become 

 extinct." 



