PRESIDENTIAL ADDRESS. 17 



Every investigator knows how small a cine will sometimes 

 lead to the unravelling of obscure problems in scientific research, 

 and no one has more frequent occasion to give earnest attention 

 to such clues than the working paleontologist. Indeed, some of 

 his best results would often have escaped him if such clues had 

 been disregarded. Such a use of even the most insignificant 

 facts is perfectlv legitimate ; but I wish to refer especially to the 

 practice which has prevailed of publishing what are ostensibly 

 conclusions which have been reached from legitimate investiga- 

 tion, when in reality they are at best little more than mere 

 surmises. I will give a couple of instances of this kind to 

 illustrate my meaning. 



In California and Western Nevada, where the country is 

 mountainous and the rocks are much displaced and more or less 

 altered, several isolated and limited exposures of strata have been 

 found which contained a few fossil shells. At some of the 

 localities half a dozen species are represented, but at some only 

 one or two species. Most of these specimens are too imperfect 

 to serve as the basis of even a satisfactory specific description ; 

 and none of the types presumably represented by them are of 

 such a character as to give reasonable assurance of even homo- 

 taxial relationship with those of any European formation. 



The most that can be said of this meagre fauna is that it is 

 probably of Mesozoic age. And yet the equivalency of these 

 rocks with the Jurassic of Europe has been confidently asserted, 

 and broad generalizations have been based upon that assumption 

 as to the age of mountain uplifts and other great geological 

 events. 



Again, there is in the western portion of the United States 

 domain a formation which all geologists and paleontologists 

 have agreed in referring to the Jurassic period. It is true that 

 its invertebrate fauna is not full enough to afford entirely satisfac- 

 tory evidence on this point, but the rich vertebrate fauna which 



