36 THE OX AND ITS KINDRED 
joint, or carpus, are arranged in three vertical series 
with their constituents lying immediately one above 
the other, instead of alternating in the manner 
characteristic of both Artiodactyla and Perissodactyla. 
The teeth include the full mammalian number of 
forty-four ; and those of the cheek series are of the 
hillock-crowned, or bunodont, type. 
Phenacodtis is regarded as the typical representative 
of a suborder — the Condylarthra — equal in rank to 
the Artiodactyla and Perissodactyla, of which it 
has been regarded as the common ancestor, although 
this is not admitted by all naturalists. If, however, 
the genus be ancestral to the even-toed ungulates, 
it will form the lowest grade in the genealogy of 
the ox which can at present be definitely identified. 
