312 AWAL.S NEW YOliK AVAIJIJMY OF .SCIENCES 



A more serious criticism is the illegitimate and often partisan use 

 made of negative evidence. This is doubtless due to the same cause, a 

 mere book knowledge of the fossil record, and failure to examine and 

 weigh its evidence. But it is very obviously affected by a readiness to 

 rely on negative evidence that favors their theories and to ignore a vastly 

 greater amount of negative evidence that docs not. 



Dr. Gadow considers it "awkward" for -the theory of Ilolarctic dis- 

 persal of the marsupials in the Cretaceous that no survivors have been 

 recorded in the Tertiary of Asia. He prefers to believe that tlu' Aus- 

 tralian marsupials arrived via Antarctica from South America. If it is 

 "awkward" for the one theoiT, that although survivors are found in the 

 early Tertiary of both Europe and North America, none have been found 

 in Asia, then it must be equally "awkward" for the theory ih\\\ Dr. 

 Gadow supports that none have been found in Antarctica. For we know 

 even less about the early Tertiary of Asia than we do about the Antarctic 

 Tertiary. If the absence of zalambdodont insectivores in the Eocene of 

 Europe is to be assigned any weight, then equal weight should be assigned 

 to their absence from the Oligocene and Eocene of South America and 

 from the Pleistocene of Cuba, of Madagascar and South Africa. We 

 know as much about the one fauna as we do about the others. The 

 negative evidence has no weight in any of these instances; per conira, 

 the fact that zalambdodonts are known to have lived in the early l^ertiary 

 of North America (Paleocene to Oligocene) affords a presimiption of 

 their presence in the nearly allied early Tertiary faunas of Europe, just 

 as their presence in the recent faunas of Madagascar and South Africa 

 and in the Miocene of South America affords a presumption of their 

 presence in the nearly allied faunas .which immediately preceded them. 

 Equally, the presence of marsupials in the early Tertiary of Europe on 

 one side of Holarctica and of North America on the other side raises a 

 strong presumption of their presence in the intervening region of Asia 

 from which no fossils are known. They are not found in the later Ter- 

 tiary of Europe and America, so that we should not expect to find tlu!m 

 in the later Tertiary of Asia. On the contrary, the small fragnioiit of 

 evidence that we have as to the Tertiary fauna of .\ntarctica afl'ords a 

 slight presumption against the presence of mammals on that continent. 



Doctor Gadow's statement that the Chiroptera did not reach America 

 until the Pleistocene is another curious instance of the misuse of the 

 fossil record, which no one familiar with the character of our Tertiary 

 formations and the necessary limits of the fossil faunas would be likely 

 to make; nor would anyone ac((uaiiitcd witli tiic variety and specializa- 

 tion of the New World genera be inclintMl io l)('lie\c that it was all the 



