48 



THE MERYCOIDODONTID.E 



posteriorly. The malar is anteroposteriorly flexed sharply downward below the orbit. The nasals 

 are posteriorly acute, moderately broad, anteroposteriorly straight, and transversely gently convex. 

 The -pars facialis of the lacrimal bone is large and subtriangular in outline and bears a large and 

 generally deep fossa, which may invade the maxillary as well. The frontals are broad and trans- 

 versely convex on either side of the sagittal suture and are produced 10 to 12 mm. forward of the 

 lacrimal bones. The orbits are nearly circular, of medium size, and vertically situated somewhat 

 above the center of the skull, and they look mainly sidewise but also slightly upward and forward as 

 well. The temporal ridges unite behind the postorbital constriction to a point above the glenoid 

 surface. This union is somewhat variable. The sagittal crest varies in length from approximately 



Fig. 21. — Merycoidodon culbertsonii Leidy. A. Maxillary fragment with last two molars. GCT. Cat. No. 10727 

 A.N.S.P. B. Superior view of A. C. Mandibular fragment with molars. GCT. Cat. No. 10728 A.N.S.P. D. Superior 

 view of C. All figures natural size and redrawn from Leidy, 1848. These were the first specimens of the family to be 

 described and figured. 



one-third to one-fourth of the skull length. This crest is moderately high and thin. The supra- 

 occipital crest is produced aft above and beyond the occipital condyles, and the wings are wide- 

 spread. The brain case is narrow, elongated, and well rounded, without marked convexities. The 

 large external auditory meatus occupies the space between the glenoid and paroccipital processes and 

 is directed almost straight outward. The palate is wide and shallowly vaulted. The U-shaped 

 palatonarial border lies opposite the last lobe of M 3 or may be somewhat farther aft, opposite the 

 posterior edge of this molar. The glenoid articular surface is shallowly convex, while the post- 

 glenoid process is robust, with an oblique external border. The bulla is very small, about half the 

 size of the postglenoid process. The paroccipital process is subtriangular at base, L-shaped below, 

 moderately elongated, and connected with the posterior of the bulla. Index: 0.50. 



Mandible: The strong and sometimes coossified symphysis is very sloping, with a symphysio- 

 dental angle of 35°. The chin profile is but slightly concave, and the mental tubercle is present, 

 though small. The inferior border of the horizontal ramus is almost straight, and the angle descends 

 but slightly below this border. The posterior border of the ascending ramus is moderately straight 



