108 



the merycoidodontim: 



occasionally somewhat farther aft. The glenoid articular surface is large but appears to be relatively 

 small, as a result of the great expansion of the posterior zygomatic pedicle. It is gently convex 

 anteroposteriorly. The robust and truncated postglenoid process has an oblique external border. 

 The bulla is comparatively large, is subovate, and does not extend as low as the postglenoid process. 

 The uneven surface of the bulla appears to be dented. The paroccipital process is closely appressed 

 to the bulla and extends well below it. It varies from being anteroposteriorly compressed to being 

 trihedral in section. It is rather slender. Index: 0.93. 



Mandible: The chin is moderately broad and square, with a heavy rounded mental tubercle 

 and a marked concavity in profile. The symphysiodental angle is 49°. The inferior border of the 

 horizontal ramus is gently concave and blends into the angle, which has a heavy border. The ascend- 



Fig. 69. — Promerycochaerus carrikeri Peterson. Skull and jaw. PLT. 



Peterson, 1914.) 



Cat. No. 109 CM. 1/3 nat. size. (After 



ing ramus is short above the tooth row. The coronoid process is very low, like a short, blunt peg in 

 shape, and rises but slightly above the level of the condyle. The small masseteric fossa is shallow. 

 The sigmoid notch is extremely shallow and wide. The condyle is set well in from the posterior 

 border. 



Foramina: The infraorbitals lie above the posterior of P 4 . The supraorbital foramina are near 

 the sagittal plane, about 1 5 mm. apart, and from them grooves lead forward and downward. The 

 moderately large foramen ovale is close to the anterior border of the bulla, while the foramen 

 rotundum is well concealed by the external pterygoid process of the alisphenoid. 



Dentition: The incisors are small and peg-like; the canines are large and robust. P 1 and P 2 

 are isolated by diastemata. The true inferior canine is more than twice the size of the contiguous 

 third incisor. The superior molar-premolar index is 0.92 and the inferior 0.95. 



Skeleton: With the skeleton of paratype Cat. No. 1079, Peterson found what he considered to 

 be the ossified thyroid cartilage of the larynx, similar in shape to the one described by Scott as of 

 Mesoreodon. 



