48 MEMOIRS OF THE CARNEGIE MUSKUM 
Locality: White River, South Dakota ? 
Locality of Type: Academy of Natural Science, Philadelphia.° 
Principal characters of Archxotherium mortoni: The first and second incisors 
of this species are relatively large. The whole series is well spaced in both upper 
and lower jaws, which is due to the proportionally long alveolar border of the pre- 
/y YY Mia 
Uf 
HG ts 
a 
W 
il 
[] chin & AS 
ie 
AN 
pu 
Fie. 4. Side View of Skull of Archiotherium mortoni Leidy. (Carn. Mus. Cat. Vert. Foss. Skull No. 1900, Lower 
Jaw No. 2097.) 4 nat. size. 
maxillary and the long chin of the lower jaw. The canines are long and pointed, 
the premolars are compressed transversely and have comparatively high and pointed 
crowns. M® has small posterior tubercles. The lower molars have proportionally 
higher and more developed proto- and metaconids, low and little developed hypo- 
and entoconids and broad eross-valleys. ‘The posterior process of the jugal is com- 
Fic. 5. Crown View of Left Inferior Dentition of-A. mortoni Leidy. (Carn. Mus. Cat. Vert. Foss. No. 2097.) 4 nat. size. 
paratively lightly developed and does not form a buttress on the anterior margin 
of the glenoid cavity, as in some of the later genera. The anterior protuberances of 
the inferior margin of the lower jaws are slightly more developed than those further 
back. The skull represents a comparatively small-sized animal. A specimen, 
6 The specimen at this writing has no catalog number. 
