364 THE WASATCH FAUNA, 



and then nearly vertically to the base of the neck of the condyle. The 

 masseteric fossa is not defined either anteriorly or inferiorly. 



The superior incisors are slender, and the crowns are very short and 

 acuminate. The e.xternal incisor, though the largest, is not so large abso- 

 lutely or relatively as in the smaller species Mcsofii/x laniu'^: The precauiue 

 diastema large, equaling that posterior to the first superior premolar. The 

 canines are very large and have an oval section at the base lying anteropos- 

 teriorly. The crown is destitute of ridges, and the enamel is perfectly 

 smooth. The first premolar has one root with an oval section. The two 

 roots of the second are large in comparison with the crown. The latter 

 has no anterior basal lobe, has a simple cone, and a heel with cutting 

 median edge. The cone has no edges or ridges. The third premolar has 

 the .same form, with the addition of a rudimental anterior basal tubercle. 

 The heel has a wide base. The fourth premolar differs from the third in 

 having a large internal conic lobe and an anterior basal tubercle. The pos- 

 terior edge of the principal or external cone carries a small lobe ; its ante- 

 rior face is rounded. On the first and second true molars this small lobe 

 becomes a second external cone smaller than the anterior external and than 

 the internal cone, which are about equal. Botli these teeth have an ante- 

 rior and posterior basal lobes The second true molar differs from the first, 

 in that the posterior basal lobe is smaller, and that the external cingulum 

 into which it continues is wider than that of the first true molar. It also 

 extends with an interruption to the anterior basal lobe of the second molar, 

 but is rudimental on the anterior external jjart of the first. The outline of the 

 bases of both of these teeth is trifoliate, the anterior external lobe a little the 

 smallest. The posterior molar is more nearly triangular, the external part 

 of the crown having less anteroposterior extent. It supports one external 

 cone witli a small posterior basal lobe, and a posterior, external, and anterior 

 cingulum. The internal cone is well develoi)ed, but is not so large as the 

 external. None of the molars have an internal cingulum. 



Tlie crowns of the inferior incisors arc lost, but their bases are small. 

 The canines are large, and have an anteroposterior oval section without 

 angles or grooves. Enamel smooth. The first premolar is one-rooted, and 

 is directed very obliquely forwards. Tlie second and third jMcir.olars are 



