6o 



BIOLOGICAL LECTURES. 



some of the methods of investigation in vertebrate palaeontol- 

 ogy, a large subject, only the more salient points of which can 

 be touched upon in an hour's talk. Judging from the questions 

 that are asked me and from the letters that I receive, it would 

 seem that these methods are a mystery and a sealed book to 

 workers in other departments of morphology, and yet there is 

 nothing mysterious or recondite about them. They consist 

 simply in the application of patience, common sense, and man- 

 ual skill to the problems which confront us. The collector and 

 the museum preparator do the greater and heavier part of the 



Fig. 



General view of White River Bad Lands. (Photograph by Williston.) 



work; to the investigator falls the pleasanter task of studying 

 the material which has been gathered and made ready for him. 

 The indispensable prerequisite for the scientific study of 

 extinct forms is to determine the order of succession in which 

 those forms made their appearance upon the earth. If we 

 study the animals without reference to this order of succession, 

 we may learn much, it is true, but many of the interesting 

 problems will remain insoluble, and our ideas of phylogenetic 

 relationship will surely become confused and hazy. It is not 

 always easy to distinguish a degenerate from a primitive form, 

 unless we know its history, and history without chronology is a 

 chaos. Consequently, the first step to be taken in our inquiry 



