6 THE AGE OF MAMMALS 



of the earth, or uniformitarianism, had been struggling for expres- 

 sion in the writings of the French evolutionists Lamarck (Jean Baptiste 

 Pierre Antoine de Monet de, 1744-1829) and Etienne Geoffroy St. Hilaire 

 (1772-1844), as well as in the classifications of another great Frenchman, 

 De Blainville. These ideas found in Darwin their first true interpreta- 

 tion, because the geological succession, the rise of mammals, their migra- 

 tions, their extinctions, were all connected with the great central idea of 

 divergent evolution from primordial forms. The impulse which Darwin 

 gave to mammalian palaeontology was immediate and unbounded, finding 

 expression especially in the writings of Thomas Henry Huxley (1825-1895) 

 in England, of Jean Albert Gaudry (1827-1908) in France, of Edward 

 Drinker Cope (1840-1897) and Othniel Charles Marsh (1831-1899) in 

 America. 



The first fine exposition of the new spirit of the period as applied to 

 extinct Mammalia is Gaudry's Ajiimaux Fossiles et Geologie de VAttique 

 (1862), based on the Upper Miocene fauna of Pikermi near Athens. This 

 work, to which we shall make many references, is full of genius. Espe- 

 cially noteworthy is Gaudry's discovery that mammals in their descent 

 or phylogeny follow not one but many contemporaneous and parallel 

 lines. In other words, Gaudry first enunciated the polyphyletic law as 

 applied to mammals, but singularly his subsequent writings were not con- 

 sistent with this law. 



The remarkable memoirs of Vladimir Onufrievich Kowalevsky (1842- 

 1883), published in 1873, are monuments of exact observation of the details 

 of evolutionary change in the skull, teeth, and feet, and of the apprecia- 

 tion of Darwinism. In the most important of these memoirs, entitled 

 Versuch einer Natiirlichen Classification der Fossilen Hufthiere (1873), we 

 find a model union of detailed inductive study with theory and working 

 hypothesis. These works swept aside the dry traditional fossil lore which 

 had been accumulating in France and Germany. They breathed the new 

 spirit of recognition of the struggle for existence, of adaptation and de- 

 scent. 



Huxley's most vital contribution was his development of the method 

 of palceontology, or the modes of examining and testing facts, of synthesis 

 and analysis. These may now be studied in his collected memoirs.^ His 

 principles of analysis are complete except in his failure to realize the 

 wonderful operation of the law of analogy in the repeated creation of 

 similar forms from dissimilar ancestors. 



All these writers attacked the problem of descent, and published pre- 

 liminary phylogenies of such animals as the horse, rhinoceros, and ele- 

 phant, which time has proved to be of only general value and not at all 

 comparable to the exact descent series which were being established dur- 

 ing the same period by invertebrate palaeontologists, beginning with the 



' Scientific Memoirs of Thomas Henry Huxley, 4 vols, London, 1898-1903. 



