THE STUDY OF STRUCTURE. 351 



by Cope and Osborn, is certainly that of an old- 

 fashioned Ungulate, with some affinities to other 

 stocks, and perhaps one of the earliest ancestors of 

 the horse. The skeleton of Archceopteryx, in the 

 lithographic slates of Solenhofen, carefully studied 

 by Dames and others, is certainly that of a bird with 

 more distinctly reptilian affinities than any living 

 form shows. The skeleton of Palceospondylus, from 

 the Devonian of Caithness, discovered and described 

 by Traquair, is certainly that of a tiny primitive 

 vertebrate, whose real reconstruction from many spec- 

 imens has been a triumph of palaeontological skill. 

 And thus we might continue, for nineteenth-century 

 palaeontology has made it abundantly clear that links 

 are not always missing. It would be absurdly pessi- 

 mistic to suppose that there are not many still await- 

 ing discovery. 



Evolutionary Palaeontology. The doctrines of 

 the Cuvierian school dominated most of the palae- 

 ontological work of the first half of the nineteenth 

 century. The work of Owen, Louis Agassiz, and 

 Bronn was in some respects transitional, for though 

 none was a thorough-going evolutionist, they all had 

 an idea of progressive development. The dawn of 

 evolutionary palaeontology practically dates from 

 Darwin's Origin of Species (1859), and now it may 

 be said that almost all palaeontologists are keen evo- 

 lutionists. 



Von Zittel says : " To determine the genetic re- 

 lationships, the ancestry, the modification, and the 

 further development, in short the race-history or 

 phylogeny, of the organisms under consideration is 

 now regarded as the essential, by many, indeed, as 

 the chief aim of palaeontology." 



Traquair says : " From the nature of things it 



