No. 2391. DESCRIPTIONS OF PLEISTOCENE VERTEBRATA— HAY. 635 



molar, but no traces of others or of their backwardly directed canals. 

 It is possible, however, that these were lower down than in the part 

 of bone preserved, (d) In no felid that the writer has found does the 

 symphysis on its upper surface, extend backward beyond the front 

 of premolar 3. In the fossil fragment the curvature of the surface 

 indicates that the upper face of the symphysis reached back at least 

 as far as the middle of the anterior premolar. It appears improb- 

 able, therefore, that this fragment was that of a jaw of any of the 

 Felid ae. 



Now as to the larger fragment of the jaw: (a) In the cats the lower 

 border of the ramus is nearly straight from the symphysis to the 

 angle, so that, when placed on a level surface, the angle touches the 

 surface or nearly so. The upper and inner border of the jaw along 

 the tooth row then slopes slightly downward. When the fossil 

 ramus is placed on a level surface the inner upper border of the bone 

 slopes slightly upward in front. Unless the jaw below the anterior 

 teeth maintained the great depth which it has behind, 51 mm., the 

 angle of the jaw must have been raised above the supposed level 

 surface. (6) In the cats the surface for the insertion of the masseter 

 muscle is nearly always deeply excavated, and the bone at the lower 

 edge of this surface stands out as a sort of shelf. In the fossil the 

 masseter surface is less deeply excavated, (c) In the cats, so far as 

 observed, the depth of the jaw at the middle of the molar is consid- 

 erably less than the length of the sockets of the last premolar and the 

 molar taken together. In the fossil the two dimensions are equal. 

 The characters just discussed, it seems to the writer, make it very 

 improbable that the jaw belongs to Felis or any closely related genus. 



The general appearance of the fragments, the similar fossilization, 

 the filling of sediment in the canals and other openings, the size of the 

 small fragment relative to the larger one, and the improbability that 

 either of them belonged to a felid, make it probable that they were 

 parts of the same jaw. 



If this is the case, it appears that the jaw must be referred to the 

 Hyaenidae, for there are three premolars, all two-rooted, the hinder- 

 most large, and a large molar, doubtless a shearing tooth. The 

 diastema is short, as in the hyaenas. In Crocuta the symphysis comes 

 back even with the middle of premolar 2, as it does in the fossil. There 

 is a large single mental foramen in the position of that of the fossil. 

 The lower border of the ramus rises from beneath the molar to the 

 angle; and this was probably the case with the fossil jaw. The mas- 

 seter excavation is comparatively shallow, as it is in the fossil. On 

 the outer face of the jaw, beneath the molar and the last premolar, 

 the surface is somewhat concave in the hyaenas; in the cats it is con- 

 vex; in the fossil it is concave. The inferior dental foramina and 

 canal in the cats are large; in the hyaenas they are much smaller. 



