324 REPORT OF NATIONAL MUSEUM, 1892. 



pie, abundant remains of a flora, consisting- of types which in Europe 

 are characteristically Tertiary, are found in American strata, which 

 are shown by all other known evidence, which is abundant, to be of 

 Cretaceous age. Again nonplacental mammalian remains of generally 

 accepted Jurassic types are found in American strata which other 

 evidence shows can not be of earlier age than the uppermost ( Creta- 

 ceous, if, indeed, they are not of Tertiary age. Associated with these 

 mammalian remains are those of dinosaurs which are so characteristic 

 of that great subclass in its prime, and show so little evidence of its 

 decadence that when they were first discovered they were believed to 

 be of Jurassic age. 



The cause of this association of types in the strata of certain sys- 

 tems, or in those of certain of its divisions as they occur in some parts 

 of the world with those which characterize other systems or others of 

 their divisions in another part, must be sought in the facts and princi- 

 ples stated in the propositions and remarks on pages 203 to 300, which 

 propositions have been presented for the purpose of such reference. 

 From the facts thus stated and referred to it may be seen that such a 

 commingling of types, so far from being an abnormal condition, is 

 wholly natural and what ought to be expected. It is thus shown that 

 the average rate of progressive evolution which produced the types 

 that characterize the different systems and their respective divisions 

 was not the same in all parts of the world for each of the different 

 branches of the animal and vegetable kingdoms, nor the same for the 

 same part of the world during all the time those branches have 

 coexisted. 



In view of the foregoing statements of facts and principles the idea 

 held by the early geologists, as well as by some of those now living, 

 that identity of fossil types proves synchronism or exact contempora- 

 neity of origin of any two or more series of strata containing them, is 

 quite untenable. The facts which have been presented also suggest 

 that the term hoinotaxy must be used with some degree of latitude as 

 to its application to the subdivisions of systems, because the order of 

 sequence in the occurrence ot the types which characterize them, 

 respectively, in one part ot the world is in another part sometimes par- 

 tially reversed or partially interchanged. That is, the taxonomy of 

 those subdivisions as biologically indicated is not the same for all parts 

 of the world. 



Although the toregoing statements contain expressions of earnest 

 dissent from certain views which have been more or less prevalent, it 

 is not to be inferred that I discard any of the legitimate principles 

 upon which correlative and historical geology are based. Indeed, the 

 evidence is incontestable that the successive stages of the geological 

 scale were in a general but an effective way characterized by peculiar 

 secularly developed groups of organic types, and that those types have 

 wonderfully wide distribution within their respective stages. With 



