494 THE EOCENE PERIOD. 



other of the areas of the Wasatch deposits, but it occurs abundantly in its 

 locahty, so that it is possible to determine its general structure. 



a i» -I A q 



Dental formula, I. ^- : C. - : Pm. - ; M. - ; without diastema. Inci- 

 3 1 4 '6 



sors and canines in both jaws small. Fourth superior premolar unlike first 

 true molar. Fourth inferior premolar like first inferior true molar. Third 

 inferior true molar without third lobe or heel. Superior incisors with small 

 oval crowns. Inferior incisors with short depressed crowns. First and 

 second superior premolars without internal lobes. First, second, and third 

 inferior premolars without internal lobes. True molars supporting two 

 external Vs, which are separated by a vertical ridge. Two internal lobes ; 

 the anterior conic, the posterior crescentic, the anterior horn of the cres- 

 cent connecting with a central intermediate lobe, so as to form an oblique 

 cross-crest on wearing An anterior intermediate lobe forming a crescent 

 concentric with the anterior V. Last superior molar without the posterior 

 internal V. Fourth superior premolar with two external Vs, two interme- 

 diate lobes,, and an internal cone. Third superior premolar with external 

 wall and internal cone. 



First inferior premolar one-rooted; third, two-rooted, with compressed 

 crown. Fourth premolar and true molars consisting of two Vs, whose adja- 

 cent limbs join each other. Inferior canine incisor-like. 



Orbits widely open posteriorly. Palate excavated between the molars 

 posteriorly. A postglenoid process. Auricular meatus widely open below. 

 Posttympanic and paroccipital processes united. Occipital and sagittal 

 crests. Foramen ovale scarcely separated from / lacerum anterius. Man- 

 dibular symphysis coossified. Mandibular condyle uplooking. Brain not 

 so small as in Phenacodiis. 



The cervical vertebrae are, like those of Phenacodus, of medium length, 

 and slightly opistheocoelous. They, with the lumbars, have an inferior keel. 

 The disparity in size between the anterior dorsals and lumbars is marked. 

 The odontoid process is cylindric. Metapophyses of lumbars well marked. 

 No anapophyses. The neural canal is rather large. 



The head of the scapula has a curved coracoid process. The spine 

 rises abruptly from the neck. The humerus is much like that of Phenaco- 



