The Zoology of North American Big Game 



elephant, but not so thick," and even but a few 

 years back all that was considered necessary to 

 answer the question, "what is a bison ?" was to state 

 that it is a wild ox with a shaggy mane and a hump 

 on its shoulders, and the thing was done; but in 

 our own time a satisfactory answer must take ac- 

 count of its relationship to other beasts, for we 

 have come to believe that the differences between 

 animals are simply the blank spaces upon the chart 

 of universal life, against which are traced the re- 

 semblances, which, as we follow them back into 

 remote periods of geologic time, reveal to us 

 definite lines of succession with structural change, 

 and these, correctly interpreted, are nothing less 

 than actual lines of blood relationship. To know 

 what an animal is, therefore, we must know some- 

 thing of its family tree. 



It is perhaps well to emphasize the need of cor- 

 rect interpretation, for there are no bridges on the 

 paths of paleontology, and as we go back, more 

 than one great gap occurs between series of strata, 

 marking periods of intervening time which there is 

 no means of measuring, but during which we know 

 that the progress of change in the animals then 

 living never ceased. When such a break is 

 reached, the course of phylogeny is like picking 

 up an interrupted trail, with the additional compli- 



53 



