46 WHAT EVOLUTION IS 



much interested in the fossil series 

 illustrating the evolution of the horse. 

 As is well known, this animal can be 

 shown to have descended from a small 

 multi-toed creature of the approxi- 

 mate size of a fox. In the early days 

 of the evolutionary controversy this 

 was the one series of developing forms 

 that the paleontologist could point to 

 with assurance. To-day scores of 

 such series are known not only in the 

 vertebrates but in the invertebrates. 

 Even with man the call for the miss- 

 ing link seems to have subsided, for the 

 sequence in so many of the fossil series 

 is so nearly complete that it seems to 

 be only a matter of diligence and time 

 till the fossil record of any important 

 line can be brought to light. The imper- 

 fections in the fossil series are no longer 

 interpreted as real and significant 

 breaks but as interruptions sooner or 

 later to be filled as science advances. 



