220 . M. R. Thorpe— New Species of 



Hoplophoneus molossus, sp. nov. 



(Figs. 4 A-C). 



Holotype, Cat. No. 10052, Y. P. M. White Eiver (Oligocene), White Eiver, 

 Nebraska. 



This species is based on an almost complete skull, both, 

 mandibular rami, atlas, axis, third cervical, eleventh, 

 twelfth, and thirteenth dorsals^ and the first lumbar. 

 Fragments, probably of the sixth, twelfth, and thirteenth 

 ribs, were found with the specimen, which was collected 

 in 1875 by H. C. Clifford. The specimen is an adult and 

 has suffered a small amount of distortion, but not enough 

 to interfere with the general outline and characters of 

 the skull. Both canines are broken off about midway of 

 their length. 



This species is most closely allied to H. primcevus. 

 The basal length is approximately 10 mm. shorter, while 

 the prosthion-nasion dimension is also less by 10 mm. 

 than in H. primcevus, but the breadth of the anterior 

 nares is greater by 4.5 mm. and the interorbital breadth 

 is less by 5 mm., thus showing a different facial aspect. 

 The post orbital constriction differs by 8 mm., H. primce- 

 vus having the greater diameter. The bimastoid diame- 

 ter is 10 mm. less in this specimen. The ratio of the 

 anterior zygomatic pedicle in H. primcevus is 143, but in 

 this species it is 109. The depth of the ramus of this 

 species, posterior to P 4 , is greater by nearly 3 mm. The 

 maximum diameter of the superior canine at the alveolus 

 is 3.5 mm. greater, while the length of the base of the 

 crown of P 4 is 1.5 greater, and the distance between 

 P 3 and M l5 inclusive, is 3 mm. greater than in H. 

 primcevus. 



One very obvious difference between this species and 

 the nearest to which it bears resemblance is the heavy, 

 massive bones which make up all parts of the specimen. 

 The cranial capacity is small and the very small diameter 

 of the postorbital constriction is very noticeable, as well 

 as the important relations existing between the pedicle 

 dimensions. The face is broad, and the cranium narrow, 

 while the reverse is true of H. primcevus. 



The atlas and axis will be briefly described. The atlas 

 resembles that of Felis and yet is primitive in some 

 characters. There are no alar notches and the dorsal 

 arch has a distinct spine, which is massive and rounded, 

 rather than oblong-shaped. The maximum diameter be- 



