176 



THE MERYCOIDODONTID/E 



parietal suture, that is, over the posterior part of the glenoid tubercles. The sagittal crest is very 

 short; it is low, rising a little just in advance of the supraoccipital crest, and is narrow. The supra- 

 occipital crest overhangs the condyles, and the wings are not widely expanded but appear to be much 

 as they are in M. cursor. Below these the occiput is broad, and on either side, about halfway 

 between the occipital condyles and the top of the skull, there is a deep concavity. The brain case is 

 markedly elongate and well rounded. The external auditory meatus is large and is outwardly and 

 posteriorly directed. The palate is narrow and gently concave, while the U-shaped palatonarial 

 border is situated far behind the last molars. The basicranial axis is moderately steep. The glenoid 

 surface is nearly flat. The postglenoid process is unusually slender and narrow transversely. It is 

 concave posteriorly, in consequence of the broad channel leading from the postglenoid foramen. 



Fig. 128. — Merycoides longicefs (Douglass). 



Inferior view of skull. HT. 

 (After Douglass, 1907.) 



Cat. No. 9732 A.M.N.H. 2/5 nat. size. 



The paroccipital process is prismatic in cross section, with anteroposterior and transverse diameters 

 nearly equal. Distally the paroccipital processes are laterally compressed, and they bend slightly 

 forward and outward. The bulke were large, but the lower parts are broken away. Index: 0.50. 



Mandible: The inferior border of the horizontal ramus increases in depth posteriorly, so that 

 the angle is not so clearly demarcated as it is in most of the oreodonts. The symphysis is gently 

 concave vertically and convex transversely. The chin forms an angle of 40° with the tooth row, as 

 in M. cursor. The ascending ramus is broad anteroposteriorly, and the condyle is gently convex and 

 not offset. The coronoid process is thin and low, but the sigmoid notch is less shallow than in the 

 other species. The shallow masseteric fossa is relatively smaller than in M. cursor. 



Foramina: The infraorbitals are above the interval between P 3 and P 4 , and the supraorbitals 

 are moderately large, nearer to the median suture than to the supraorbital margin and with shallow 

 grooves as far as the nasal bones. The foramen ovale is large and is apparently farther forward 

 than in most of the oreodonts, but this is probably on account of the unusual lengthening of the 

 posterior part of the skull. I have not seen any foramen rotundum in this specimen. The posterior 

 palatines are opposite the anterior half of M 1 , while in M. cursor they are opposite the interval 

 between P 4 and M 1 . 



Dentition: The teeth are brachyodont, with a suggestion of hypsodonty, and the molar series 

 are longer than the premolar (index 0.80, the lowest of the genus). The incisors are small. The 

 canines are more robust than in M. cursor, more like those in M. latidens. They have a vertical 

 groove on the inner side. The anterior three premolars increase regularly in size posteriorly and in 

 the development of the crown pattern. The molars likewise increase regularly in length, width, and 

 height. 



