342 Bulletin American Museum of Natural History, [^'ol. XXVII, 



CHAPTER IX. GENETIC RELATIONS OF THE UNGULATA 



AND SIRENIA. 



Analysis. 



Page . 



I. Outline history of the ordinal classification 342 



II. The Condylarthra 354 



III. Genetic relations of the Condylarthra, Taligrada and Amblypoda . . 356 



IV. The Hyracoids 360 



V. The Embrithopoda 364 



VI. The Proboscidea 366 



VII. The Barytheria (Incertse Sedis) 369 



VIII. The extinct South American groups Homalodontheria, Astrapotheria, 



Toxodontia, Typotheria, Litopterna, Pyrotheria 369 



IX. The Perissodactyla and Ancylopoda 385 



X. The Artiodactyla 400 



XI. The Sirenia 406 



XII. General conclusions 409 



I. Outline History of the Ordinal Classification. 



The systematic history of the term "Ungulata" and its correlative, 

 " Unguiculata," may be said to begin in 1696 when Ray employed these 

 terms in his dichotomous table of the hairy viviparous quadrupeds (c/. p. 18 

 above). TJnnseus emended the terms in 1766 by transferring Camelus and 

 Elephas from the Unguiculata, where Ray had placed them, to the Ungti- 

 lata. At the same time he erected the coordinate division "Mutica" to 

 include the Cetaceans. With more or less varying content "Unguicidata," 

 and "Ungulata" were used by many subsequent authors {e. g., Storr, 

 Blumenbach, Owen, Cope) down to the present time. 



It was early realized that "Unguiculata," covering Monotremes Marsu- 

 pials and unguiculate Placentals (including the Primates) was in its original 

 signification an imnatural assemblage, and by many authors (e. g., Blumen- 

 bach, Illiger, de Blainville) it was not used in a systematic sense. In 

 modern times it has been tacitly recognized by many that even after the 

 restriction of the term to include only the unguiculated Placentals it is still 

 only a partly natural residuum, since it embraces such widely removed 

 orders as the Edentates, Bats, Carnivores, etc. The following studies tend 

 to the conclusion that the term "Ungulata" likewise includes a group of 



