88 Bulletin Ayncrican Museum of Natural History. [Vol. XXVII, 



this epoch (c. g., Haeckel) and even now are only gradually being 



recognized. 

 Analysis of the results of parallel, divergent and convergent evolution 



in their bearing on classification (e. g., Cope, Scott, Osborn, Dollo) and 



of the principles of adaptive radiation and homology (Osborn). 

 Search for inconspicuous, slowly changing, " paleeotelic " characters as 



being better indices of affinity than conspicuous superficial, " caeno- 



telic " characters. 



GENERAL PROGRESS OF THE ORDINAL CLASSIFICATION OF THE MAM- 

 MALIA SINCE 1859. 



As already noted the history of mammalogy reveals a continuous interplay 

 between the " ecole des faits " and the " ecole de idees." Gesner, Daubenton, 

 Illiger, Flower, Zittel, and Marsh may be taken as types of men whose 

 prime business was the accumulation and orderly presentation of facts with 

 only incidental reference to theories; Ray, Linnjieus, Cuvier, de Blainville, 

 Huxley, on the other hand, represent the "ecole des idees," who in one Avay 

 or another profoundly influenced the interpretation of facts. 



Although Darwin's name is rightly given to the epoch under consideration 

 yet he did not himself apply the doctrine of evolution to the problem of the 

 classification of the mammals. The publication of the 'Origin of Species' 

 did not therefore at once produce its permanent effects upon mammalogy; 

 Haeckel's earlier phylogenetic trees, based too largely upon placental char- 

 acters, did not stand the test of time; and it was not until 1880 that Huxley 

 made his well known 'Application of the Principles of Evolution to the 

 Arrangement of the Vertebrata and more particularly of the ]\Iammalia,' 

 an analysis which ]>artly formulated the methods for correct phylogenetic 

 conclusions respecting interordinal relationships (see below, p. 94). 



Through the discovery of the great fossil faunas of India, North and 

 South America, and more recently of North Africa, mammalogy came into 

 possession of a vast number of new facts which at the present day are still 

 very incompletely assimilated. Several far reaching principles, however, 

 have slowly emerged. Cope (1890 p. 98) and Scott (1891) formulated 

 the theories of parallel and convergent evolution, Osborn has developed the 

 ideas of adaptive radiation, both general and local, and of poh^^hyletic 

 evolution (1902-10). The general evolution of the teeth and of the feet in 

 the Mammalia has engaged the attention of many investigators. The 

 evolution of the carpus and tarsus was studied by Kowalevsky (1873), 

 Cope (1887), Baur (1885-86) Weithofer (1888), Osborn (1889), Rutimeyer 

 (1890), Matthew (1895), and the subject is reviewed and extended in the 

 present work (pp. 438-457). 



The evolution of the cheek teeth, first sketched by Huxley (1881), 



