466 THE WASATCH FAUNA. 



becomes the anterior edge of a beveled border of the convex angle of the 

 jaw, which ceases on reaching- the inferior surface. The face of the con- 

 dyle is transverse and narrow, and presents exclusively superiorly. The 

 base of the coronoid process is narrow fore and aft. The masseteric fossa 

 is well marked, excavating the ascending ramus above the line of the teeth; 

 below this it is only defined for a short distance in front by a downward 

 continuation of the anterior ridge. Symphysis not coossified. There is a 

 single mental foramen, which is below the first inferior premolar. 



Dentition. — The first and second incisor teeth are very similar, and 

 different in the form of the crown from the third. The crowns are ex- 

 panded anteroposteriorly, so as to touch each other, although the roots are 

 separated But there is a space nearly equal to the lengths of the edges of 

 both crowns between those of the first incisors of opposite sides. Wearing 

 makes the edges of the first and second acute. The third incisor is equal 

 in size to the others, but its crown is canine-like, and with recurved apex. 

 A short space separates this tooth from the canine, and the alveolar edge is 

 arched upwards to receive the crown of the inferior canine. The canine is 

 not large. Its crown has a spherical triangular section, the posterior edge 

 not acute. 



The first premolar leaves a single rather large oval alveolus, which 

 occupies the space between the canine and the second premolar. The latter 

 has a simple crown, which is a triangle in profile. Its base is wider poste- 

 riorly than anteriorly, but there are no accessory tubercles. • The anterior 

 and posterior edges are subacute. The base of the crown of the second 

 superior premolar is nearly a right-angled triangle, the posterior and exte- 

 rior edges contributing to the right angle. The external face of the crown 

 is flat and triangular in shape, a slight convexity indicating the basis of a 

 small posterior external tubercle worn off by mastication. The internal 

 cusp is also worn off. Its base is entirely posterior. The base of the 

 fourth premolar more nearly approaches an isosceles spherical ti-iangle, the 

 posterior border being a little more convex than the anterior. The external 

 cusps have subequal bases, which have a round section on attrition. The 

 internal cusp has a semicircular section on wear. There is space for a pos- 

 terior intermediate tubercle, but if it were present, it is worn off. Anterior 



