248 



the merycoidodontim: 



on the zygoma. The palate is wide and very slightly vaulted, with the V-shaped palatonarial 

 border just a little in advance of a line across the posterior of M 3 . The basicranial axis is shallow, 

 and the bullae are apparently the largest in the whole group of Merycoidodontidse. The glenoid 

 surface is wide anteroposteriorly and gently convex downward. The whole basicranial region is fore- 

 shortened, and the small postglenoid is made up of two bones, as in Leptauchenia. The paroccipital 

 process is wide transversely and is stocky at the base, rapidly tapering downward. Index: 0.72. 



Fig. \76.—Cyclofidius lullianus Thorpe. Right half, inferior view of skull. HT. Cat. No. 10117 Y.P.M. 



2/3 nat. size. 



Mandible: The rami are massive, deep, and heavy. The inferior border is much thickened, 

 and, below the anterior molars, there is an osseous tubercle on each ramus. The position of this is 

 suggestive of the entelodonts, except of course that in the latter the size of the tubercle is very much 

 greater. The symphysiodental angle is about 45°. The symphysis was heavy and probably coossi- 

 fied. The masseteric fossa is extensive but shallow. The coronoid process is short and transversely 

 slender, and curves backward at the tip in a hook. The sigmoid notch forms a semicircle, and the 



Fig. 177. — Cyclofidius lullianus Thorpe. Inferior dentition. HT. Cat. No. 101 17 Y.P.M. Nat. size. 



condyle is rather small and is quite convex upward. The posterior edge of the ascending ramus is 

 vertical for nearly half its length, and the angle descends but slightly below the inferior border of 

 the horizontal ramus. 



Foramina: The infraorbital lies above the middle of P 3 . The supraorbital is close to the 

 temporal ridge and is about midway between the sagittal suture and the supraorbital margin. 



Dentition: The dentition is markedly hypsodont; in fact, relative to the size of the skull, the 

 teeth are longer than those of any other oreodont. The molars are large, the combined length of 

 M 1 and M 2 about equalling the total length of the premolars. This is true in both upper and lower 

 series, including Pi in the latter. The upper premolars are crowded but not obliquely set, and 

 there is a diastema of 2 mm. between C and P 1 , whereas P :i and P 4 overlap. The small incisors are 

 nearly cylindrical in section and are spaced, rake-like. P 4 appears to be a half molar, formed by 

 the development of the posterior half of the tooth at the sacrifice of the anterior. This is of course 



