636 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



vol. 59. 



Those of the fossil jaw appear to have been about as large as in the 

 hyaenas. 



There are some features in the jaw which are different from those of 

 both the felids and the existing hyaenas. The jaw is deeper still than 

 in the hyaenas and it is considerably thickened along that part of the 

 lower border preserved. The angular process is strongly developed, 

 round, rather thin, and without the concavity seen on the inner face 

 of the angle of the hyaenas. While it seems that the animal must 

 be referred to the Hyaenidae, it seems quite as necessary to put it in 

 a new genus. The name of this makes allusion to the Grand Canyon, 

 whose beginning this animal may have witnessed. 



CHASMAPORTHETES, new genus. 



Type species. — Chasmaporthetes ossifragus, new species. 



Diagnosis. — Differs from the existing genera in having apparently 

 thinner premolars and molars, a deeper and thicker lower jaw, with 

 a broad and rounded angle. 



CHASMAPORTHETES OSSIFRAGUS, new species. 



Plate 124, figs. 5, 6. 



Type specimen. — The rear of the left ramus of a lower jaw, with 

 roots of teeth, but with the crowns shattered. (Cat. No. 10223.) 



Type locality. — Coconino Forest region, Arizona. 



Type formation. — Early Pleistocene. 



Diagnosis. — Fourth premolar and first molar of nearly the same 

 length; the molar apparently thicker. Jaw deeper and thicker than 

 in existing species. Referred second molar two-rooted and its socket 

 nearly two-thirds as long as that of the molar. Symphysis extending 

 back to at least the middle of the second premolar. 



The following measurements in millimeters are added to the 

 description : 



Measurements of jaws and teeth of hyaenas. 



Width of canine 



Length of diastema 



Second premolar, length of socket . . . 



Third premolar, length of socket 



Third premolar, width off ront root . 

 Fourth premolar, length of socket . . . 



Fourth premolar, width of roots 



First molar, length of socket 



Width of its front root 



Width of its hinder root 



Depth of jaw at middle of last molar 

 Thickness of jaw below last molar. . . 

 Length of premolar-molar series 



Chasma- 

 porthetes 



11± 

 10 

 IS 

 19 



7 

 25 



8 

 27 



8 



G 

 49 

 17 

 90± 



Hyaena. 



10.5 

 10.2 

 13.5 

 17.2 



9 

 17.5 



9 

 17 



8 



6 

 37 

 11 

 70 



