NIMRAVIDJS. 965 



the posttympanic, where it turns forwards and becomes the acute supra- 

 meatal crest. The two tuberosities on the superior border of the foramen 

 magnum are rudimeiital. The paroccipital process is directed posteriorly. 

 It is acute and rather long, is convex behind and flat in front. The post- 

 tympanic is short, and its extremity forms an obtusely rounded tuberosity. 

 There is an osseous tuberosity below the meatus of the ear which is doubt- 

 less the same as the piece in the Archceliiriis debilis which I identified with 

 the tympanic bone. The basioccipital is divided by a median keel, while 

 the basisphenoid is smooth. The palatal surface is injured in this specimen. 



The ramus of the mandible is longer, deeper, and more compressed 

 than in the recent species of Uncia and the Pogonodon platycopis. It is more 

 robust than in the Archcelurus debilis, and the exostosis below the last two 

 molars is wanting. It is represented by a thickening of the external alve- 

 olar border, which is larger in some specimens than in others. The inferior 

 border is gently convex below the teeth, and rises slightly below the anterior 

 part of the masseteric fossa. It is continued into the hooked angular pro- 

 cess, which is as wide as deep,. and is not incurved. Anteriorly the inferior 

 border is continued as an obtuse angle slightly everted but not in the least 

 decurved below the diastema, and it then rises, running obliquely forwards 

 and forming the obtusely angular border of the flattened symphyseal region. 

 The inferior border of the symphysis descends below the level of the inferior 

 border of the ranuis. The condyle measures half the distance between the 

 angle and the summit of the coronoid process. The latter is wide and is 

 obtusely rounded above, where it does not extend posterior to the vertical 

 line from the condyle The masseteric fossa is deep and wide ; its narrow 

 anterior border is reverted, while the inferior region is excavated abruptly 

 below the general plane. There is a secondary fossa in its posterior part 

 whose superior boundary marks half the distance between the last molar 

 tooth and the summit of the coronoid process. 



Sutures. — The premaxillary bone rises in its narrow portion to the hori- 

 zontal line of the superciliary border. The maxillo-frontal suture is regu- 

 larly convex upwards, and its anterior extremity falls short of the premaxillo- 

 maxillary suture by .008 m. The nasomaxillary extends farther posteriorly, 

 i. e., to above the anterior third of the orbit, the palate and basioccipital 



