54 MEMOIRS OF THE CARNEGIE MUSEUM 
Scott as “ Hlotheriwm ingens.” Scott states (87, p. 274) that the upper incisors “in- 
crease regularly in size from the first to the third, the latter being much the largest 
of the series ; it has a conical or somewhat trihedral crown and resembles a canine 
Fig. 9. Restoration of Skeleton of A. ingens Leidy. About ;'; nat. size. (After Scott. ) 
in shape and appearance. . . . The other incisors have spatulate crowns, with 
blunted tips, the attrition of use wearing down the apices as well as the posterior 
faces of these teeth. ‘This description applies more particularly to the larger White 
River species, such as EH. ingens and E. imperator; in E. mortoni the upper incisors 
are of more nearly equal size and more conical shape.” In speaking of the upper 
premolars the same author states (J. ¢., p. 275): “In the smaller species of the genus 
such as E. mortoni, P? and P4 are placed close together, while in the larger forms 
these teeth are separated by a short space and the diastemata between the other 
premolars and between P+ and the canine are relatively somewhat greater, the 
enlargement of these teeth hardly keeping pace with the elongation of the muzzle.” 
The general contour of the skull in E. ingens is somewhat different from other species 
especially those from the lower beds. Thus, Scott (J. ¢., p. 280) states: “In most 
American species the forehead rises very gradually and gently behind to the sagittal 
crest, but in H. ingens the rise is much more sudden and steep.” The dependent proc- 
ess of the jugal “descends from beneath the orbit downward and outward to below 
the level of the ventral border of the mandible [and] forms a club-like thickening 
at the tip, which . . . is coarsely crenulate on the posterior border. . . . In E. ingens, 
