Oligocene (White River) Felidce. 217 



than in H. robustus. Considerable importance should 

 be attached to the proportions of the anterior zygomatic 

 pedicle. 



The atlas and axis of this specimen are worthy of 

 description. The maximum diameter between the ex- 

 ternal margins of the transverse processes of the atlas 

 is 78.5 mm.; the measurement from the margin of the 

 anterior articular surfaces to the posterior tip of the 

 transverse process is 47 mm. and the maximum diame- 

 ter across the anterior articular surfaces is 44 mm. The 

 maximum height is 25 mm. and the thickness of the 

 dorsal arch is 8 mm. The ventral tubercle is not as 

 sharp as in the Canidae, but is gently rounded. The 

 dorsal arch is massive and domed so that no distinct 

 spine is noticeable, thus differing from the modern 

 Felidse. The alar notches are very shallow, and the 

 transverse processes are stout and massive on their inner 

 posterior margin. 



The axis has a very long spine, its length being 

 66.5 mm., whereas the length of the centrum proper is 

 33 mm. The odontoid process is stout and heavy. It is 

 12 mm. long and its transverse diameter is the same at 

 its junction with the centrum while its vertical diameter 

 is 7.25 mm. The width across the posterior articular 

 surfaces is 24 mm., and across the anterior articular sur- 

 faces 34 mm. The vertebrarterial foramen is nearly ver- 

 tically oval, its maximum diameter being 5.5 mm. and 

 its horizontal diameter 2 mm. The transverse processes 

 are long and slender. 



No mandibular rami were found with specimen No. 

 10050, but a right ramus, together with parts of both 

 superior molar series and contiguous portions of the 

 palate, are here referred to this species. These remains 

 bear the number 10949. The ramus possesses the third 

 and fourth premolars and the first molar in good condi- 

 tion. The third incisor is nearly perfect, but the canine 

 is broken off. The left superior second, third, and fourth 

 premolars and the base of M 1 , together with a small con- 

 tiguous portion of the palatine and maxillary bones, are 

 present. The right P 4 , the posterior half of P 3 , and the 

 base of M 1 are present, also with a small portion of the 

 palatine and maxillary bones. The P 2 is single-rooted 

 in No. 10949, whereas in No. 10050 it is very difficult to 

 determine, as both second premolars are missing and 

 their alveoli are quite indistinct. It is unwise, however^ 

 in specific determinations, to place too much stress upon 



