28 LAND MAMMALS IN THE "WESTERN HEMISPHERE 



sense" (in Huxley's phrase) to observed facts, but by no means 

 all applications of them are to be trusted. Not to mention 

 ill-considered and uncritical work, or inverted pyramids of 

 hypothesis balanced upon a tiny point of fact, it should be 

 borne in mind that such a complicated and difficult problem 

 as the reconstruction of past conditions can be solved only by 

 successive approximations to the truth, each one partial and 

 incomplete, but less so than the one which preceded it. 



