1910.] Wagner, 1855; the Epoch of Darwin and Huxley. 87 



(Galeopithecus). 



(Cladobates (Tupaja), Ptilocercvis, Hylomys). 

 (Rhynchocyon, Gymiiura, Macroscelides, Sorex, So- 

 lenodon, Myogale). 



(Centetes, etc., Erinaceus). 



(Pteropus, etc.). 

 (Desmodus, etc.). 

 (Emballoiiura, Vespertilio, etc.). 



6. The Epoch of Darwin and Huxley. 

 Sjoiopsis. 



Ke}' to the confusion of principles of the preceding epoch furnished by 

 the idea of descent with modifications, as the basis of resemblances and 

 differences among animals (Darwin). 



Conflict of new and old principles (Huxley, Haeckel, vs. Agassiz, Owen). 



The anthropocentric classification, in which man as the measure and 

 standard of all things heads the list of organic beings, gives way to the 

 evolutionary classification, which leads from the more generalized to 

 the more specialized. 



Enormous increase in material leads to partial separation of mammalogy 

 proper, comparative anatomy, palaeontology. 



Monographic work of preceding epoch continued. 



Introduction of more exact field and museum methods in palaeontology. 



Correlation of fossil mammal horizons in different continents and develop- 

 ment of the theory of secular migrations and palaeogeography {e. g., 

 Cope, Osborn, Deperet, Matthew). 



Revision of generic and specific nomenclature on the basis of the "law 

 of priority,' initiated in its modern form by the American Ornitholo- 

 gists Committee on Nomenclature (1886) (cf. Scudder, J. A. Allen, 

 Trotiessart, Palmer, Hay). 



Discovery and development of the principles of evolution of the feet 

 (e. g., Kowalevsky, Cope, Osborn) and of the teeth (e. g., Cope, Os- 

 born). 



Reunion and integration of results of mammalogy, comparative anatomy, 

 embryology, palteontology; attempted to a limited degree by Flower 

 and Lydekker, Beddard, more completely by Weber (1904); but still 

 very far from completion. 



Descent and phylogenetic classification sought for; but decej^tive analo- 

 gies, existing to an unsuspected extent, deceive all early classifiers of 



