The Artiodactyla. 1079 
The mechanical superiority of the tritubercular type, over every 
other has been repeatedly demonstrated in its plastic capacity of 
adaptation to the most extreme trenchant and crushing functions. 
THE ARTIODACTYLA.! 
BY E. D. COPE. 
p= Artiodactyla is the suborder of the Diplarthrous Ungulata 
in which the astragalus articulates with the second row of 
tarsal bones by a ginglymus or hinge, and in which the third and 
fourth toes are equally or subequally developed.? It includes the 
Most highly modified of the Mammalia, whether we regard the 
organs of locomotion or of digestion. The antelope and deer illus- 
trate the greatest speed to which the mammal has attained. Their 
extraordinary apparatus for the digestion of vegetable substances 
which contain but a small percentage of nutritious proteids, has 
given them an extraordinary advantage, so that they are after the 
rodents, the most abundant of their class, in spite of the persistent 
persecution of the carnivorous species. They attain in the genera 
Giraffa and Bos the largest dimensions in the class, excepting only 
the Proboscidia. 
The Artiodactyla make their first appearance in the early or 
Wasatch Eocene in the genus Pantolestes Cope. A genus exists at 
a corresponding horizon in Europe. -No other genus of the sub- 
order appears with it. Its representatives steadily increase in 
numbers in the succeeding Bridger and Uinta epochs in America, 
and in the Calcaire grossier and Gypse of Europe. Some of these, 
€g., the Anoplotheriide of Europe, diverge from the line of suc- 
cession, while others, e.g., Xiphodontide, are clearly ancestors of 
later forms, In America, the Pantolestide appear as ancestors of the 
Camels especially. I now give a synopsis of the families of the 
suborder and their phylogenetic relations. 
I Superior molars tritubercular (Pantolestoïdea). 
Molars bunodont; four digits sss... Pantolestidæ. 
' Modified for the Naturalist from a paper by the author in the Pro- 
ceeds. of Amer. Philos, Society, 1887, p. 377. 
See Naturalist, November, 1877. 
