A HISTORY OF SCIENCE 



ample, a gigantic tribe, offshoots of the same stock 

 which produced the horse and rhinoceros, represented 

 the culmination of a line of descent. They developed 

 rapidly in a geological sense, and flourished about the 

 middle of the tertiary period; then, to use Agassiz's 

 phrase, " time fought against them." The story of their 

 evolution has been worked out by Professors Leidy, 

 Marsh, Cope, and H. F. Osborne. 



A recent bit of paleontological evidence bearing 

 on the question of the introduction of species is that 

 presented by Dr. J. L. Wortman in connection with the 

 fossil lineage of the edentates. It was suggested by 

 Marsh, in 1877, that these creatures, whose modern rep- 

 resentatives are all South American, originated in 

 North America long before the two continents had any 

 land connection. The stages of degeneration by which 

 these animals gradually lost the enamel from their teeth, 

 coming finally to the unique condition of their modern 

 descendants of the sloth tribe, are illustrated by strik- 

 m g lv graded specimens now preserved in the American 

 Museum of Natural History, as shown by Dr. Wort- 

 man. 



All these and a multitude of other recent observations 

 that cannot be even outlined here tell the same story. 

 With one accord paleontologists of our time regard the 

 question of the introduction of new species as solved. 

 As Professor Marsh has said, "to doubt evolution to- 

 day is to doubt science; and science is only another 

 name for truth." 



Thus the third great battle over the meaning of the 

 fossil records has come to a conclusion. Again there 

 is a truce to controversy, and it may seem to the casual 



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