224 M. B. Thorpe — John Bay Promerycochoeri, 



plane slightly behind the anterior orbital margins. The 

 supra-orbital grooves are well marked. The f rontals 

 are roughly diamond-shaped. The nasals are prolonged 

 to a point nearly above the incisors. From the palate to 

 the top of the nasal ridge at the third premolar is 62 mm. 

 measured in the sagittal plane, and the height from the 

 posterior nares to the frontal measured in the same plane 

 at right angles to the palate is 83 mm. The transverse 

 crests are farther apart than in P. macrostegus. No. 

 10978 has partly milk dentition which, in part, shows the 

 order of succession of permanent dentition to be M\ M^, 

 M'^, P^, P^, and P^. P^, C, and the incisors are broken 

 away so that the determination of their order can not be 

 made from the specimen. The mandible is of about 

 uniform depth beneath the tooth-row. The postero-inf er- 

 ior part of the symphysis lies below the interval between 

 P2 and P;^. These premolars are slightly crowded and 

 placed obliquely. The mental foramen below P2 is very 

 large, while the one beneath the interval between P3 and 

 P4 is comparatively small. The maximum length of the 

 ramus is 231 mm. The masseteric fossa is deep and its 

 inferior border does not extend below a posterior pro- 

 longation of the alveolar border. The sacrum of No. 

 10991 consists of three ankylosed vertebrae with parts of 

 both ilia attached. The fourth sacral was formerly 

 present. The length of the ankylosed vertebrae is 82 mm., 

 and the transverse diameter of sacral I is 124 mm. The 

 dorsal spines are not large. The maximum length of the 

 centra of the last lumbar is 35 mm., while the transverse 

 processes are about the same length. The height of the 

 neural canal is 18 mm. No. 10989 consists in part of a 

 nearly complete left ilium, acetabulum, and ischium, 

 with a right acetabulum, and part of the pubis. This 

 pelvis does not differ in essential respects from that of the 

 John Day Eporeodon, except in size. The length from 

 the anterior margin of the acetabulum to the end of the 

 ilium is approximately 132 mm. The diameter of the 

 acetabulum is 40 mm. The maximum diameter across 

 the pelvis, measured from the external edges at the aceta- 

 buli, is approximately 157 mm. The pubic s^onphysis 

 is not less than 60 mm., and may have been somewhat 

 more. The length of the ischium is 79 mm., exclusive of 

 the tip. This pelvis belonged to an old adult. No. 10983 

 has accessory styles on ]\P. The left style is an integral 



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