PETERSON: A REVISION OF THE ENTELODONTIDA 93 
articular facets for the atlas more wedge-shaped ; the facets are also of relatively 
less transverse and greater vertical diameter, and the transverse process is heavier. 
This enlargement of the transverse process is especially noticeable at the superior 
cy 
Fra. 35. Anterior and Superior Views of Atlas of D. hollandi Peterson. } nat. size. 
base over the posterior exit of the vertebrarterial canal where there is a blunt and 
rugose tubercle. The well defined ridge, which extends backward from the odon- 
toid process along the floor of the neural canal in Archwotheriwm, is in Dinohyus 
Fia. 36. Posterior and Inferior Views of Atlas of D. hollandi Peterson. 4 nat. size. 
converted into a broad rounded surface, which slopes backward and is interrupted 
by a rough ridge, which extends across the entire floor of the neural canal some 
® The vertical diameter seems to have developed superiorly, as the ventral projection is of about the same pro- 
portion as in Archwotherium. 
