Thorpe — Neiv Genus of Oligocene Hycenodontidce. 285 



pterygoids posterior to the suture joining the alisphenoid 

 with the palatine bones. The hamular process is repre- 

 sented by a prominent rugosity. The lacrymal bone is 

 more triangular in outline and relatively of somewhat 

 smaller extent than in A T . horridus. The external wall of 

 the infra-orbital foramen bears a forward-projecting lip 

 which is not present in any other species, so far as I am 

 aware, and certainly not in any examples of them which 

 I have seen. The postorbital processes of the frontals, 

 and the temporal ridges nearly to their junction, are very 

 rugose. The anterior orbital margin is but very slightly 

 elevated above the general surface of the lacrymal bone. 

 The posterior part of the nasal bones is more obtuse than 

 in N. horridus. A peculiar character of these nasals in 

 this specimen lies in the peninsula of these bones extend- 

 ing into the frontals near the maxillary suture, so that a 

 traverse on either side just posterior to the divergence of 

 the nasal and maxillary bones would pass in succession 

 toward the sagittal plane through maxillary, frontal, 

 nasal, frontal, and nasal bones. This may be an individ- 

 ual variation, but if so, it is an interesting one. 



Measurements. 

 (Cat. No. 10075, Y.P.M.) 



mm. 



Axial length, ant. of canine to post, of glenoid process. . . . 151.5 



Width of skull at post, of M 2 87 



Superior molar-premolar series, length 74 



Superior premolar series, length 49 



Maximum length of ramus 153.5 



Inferior molar-premolar series, length 82 



Inferior premolar series, length . . 51 



Synoptic Table. 



Neokycenodon. 



Glenoid articular surface far below basicranial plane ; superior 

 premolars four; dolichocephalic; size very large; antero- 

 external buttress on paraconid of M 3 . 

 Length of superior molar-premolar series 127-137 mm. 



N. horridus 



