POATREPHES 



201 



The brain case is of medium size, with a moderate lateral expansion. The external auditory 

 meatus is wedge-shaped, with the apex pointing downward. It is not elevated and is nearly in 

 normal position for the earlier merycoidodonts. It is, however, relatively larger and somewhat 

 more backwardly directed. The palatonarial border is well back of the tooth row, probably beneath 

 the postorbital constriction, and the palate is wide and nearly flat. The basicranial axis is steep, and 

 the glenoid articular surface is convex, both transversely and anteroposteriorly. The postglenoid 

 process is broad transversely but not very thick. The bullas are moderately large but are, as Douglass 

 describes them, "not symmetrically rounded as in several of the Oreodonts. They differ on opposite 

 sides of the same skull, and one is larger than the other. One is approximately a quarter of a four- 

 sided pyramid, with the apex pointing downward. The other approaches nearer to a cube." The 



Fig. 145. — Poatrefhes fdudicola Douglass. Skull. GHT. Cat. No. 845 CM. 1/2 nat. size. (After Douglass, 1903.) 



basioccipital has a median ridge which widens posteriorly. The paroccipital process is broad trans- 

 versely at the base, thin anteroposteriorly, concave in front, and convex, or nearly angulate, behind. 

 It is closely appressed to the bulla. The occipital condyles are small. The occipital pillar is very 

 convex and flanked by two deep concavities. Index: 0.68. 

 Mandible: Unknown. 



Foramina: The infraorbital is above P 4 , while the supraorbitals are about on a line through the 

 posterior third of the orbits and are 1 2 mm. from the sagittal suture. 



Dentition: Douglass considered the teeth "brachyhypsodont," describing them as follows: 



The two anterior incisors, judging by the remains of the alveoli, were small, the third much larger. The 

 canine was of medium size. Premolar four and the molars have extremely narrow valleys, but the teeth are 

 much worn. The molars are narrow with no ridges on the outer median surfaces of the outer crescents. On the 

 third molar the anterior and median pillars are prominent but there is no large accessory lobe at the posteroexterior 

 angle, though there is a small one. 



I might add that the parastyle of M 3 is unusually heavy, whereas the parastyles and meso- 

 styles on the other molars are what we should expect in these later forms. The premolars are not 

 crowded, in fact, their total length slightly exceeds that of the molar length, an unusual feature in 

 this family and one which may be primitive, or it may be correlated with a very long- jawed type. 

 Some of these teeth are badly damaged, so that it is difficult to make out their exact pattern, size, 

 and shape. 



Discussion: Specimens of this genus and species are rare. A fragment of a maxillary, with P 4 

 and the three molars, was found in 1898 by William T. Coffey, in the Deep River beds, near White 

 Sulphur Springs, Montana. It is Cat. No. 754 CM. and is seemingly identifiable with this species. 

 The specimen was found with a partial skeleton of Palteomeryx. 



