130 



THE MERYCOIDODOKITLVE 



An angle of 45° is formed between the sagittal plane and a line passing through the postglenoid 

 and paroccipital processes. The latter, in contact with the bullae, do not approach near to the former, 

 and below the base the long axis is anteroposterior. Index: 0.575. 



Mandible: The chin profile is very slightly concave, and the mental tubercle is not large. The 

 symphysiodental angle is 45°. The horizontal ramus appears somewhat slender for the size of the 

 skull but gradually deepens aft. Its lower border is nearly straight. The angle is not prominent, 

 and the condyle is not very much inset. The coronoid process is not much higher than the condyle, 

 and the sigmoid notch is shallow but large. The masseteric fossa is very deep. 



Foramina: The infraorbital foramina are above P 4 . The supraorbitals are 22 mm. apart. 

 The basicranial foramina are normal, and the posterior palatines are opposite P\ 



Dentition: The molars have a faint internal cingulum. The metastyle of M 3 is large. P 1 is 

 isolated, the incisors are small and the canines very large. The superior molar-premolar index is 

 0.83, and that of the lower series is 0.88. 



Discussion: In many respects this species is similar to P. superbus, except for smaller propor- 

 tions, and it may be the female form. 



Other specimens of the species were collected at Clarno Bottom and Haystack Valley, neither 

 far from the type locality. Some specimens from both localities differ in minor details from the 

 type. 



Fig. 85. — Promerycochaerus lulli Thorpe. Skull and jaw. HT. Cat. No. 1023+ Y.P.M. 1/4 nat. size. (After 



Thorpe, 1921.) 



Promerycochcerus lulli Thorpe 1921 



Figs. 85-88 



Original Reference: John Day Promerycochaeri. Amer. Jour. Sci. (5), I, p. 231, figs. 1 A, B. 

 Type Locality: Turtle Cove, John Day Valley, Oregon. 

 Geologic Horizon: Upper Oligocene (middle John Day). 



Type: Holotype, Cat. No. 10234 Y.P.M., skull, jaws, anterior cervicals, and stylohyals. Collected by 

 William Day in 1875 and named for Professor Richard Swann Lull. 



Specific Characters: The skull is nearly of the length of that of P. macrostegus but much 

 narrower. The face is narrow and deep, with the muzzle truncated. The maximum zygomatic 

 expansion is opposite the zygomatic foramen. The malar below the orbit is very deep but thin, and 

 the anterior zygomatic pedicle arises above the anterior portion of M 2 , with a convexity extending 

 forward for a short distance. The squamous process of the arch extends forward beneath the 



