158 



University of California Publications. [Geology 



20 mm. and a height of 5 mm. The symphysis is very large and 

 strong, the surface of contact being oval in shape and extending 

 far down. The coronoid process is larger and broader than m 

 S. neogaeus, and is more anterior in its position. 



The angle of the jaw is small, and therefore does not inter- 

 fere with the wide opening of the mouth. The two teeth P + and 

 M 1 are situated about the middle of the mandible and directed 

 backward obliquely at a considerable angle. The position of 

 the teeth is important in the comparison with South American 

 species. 



The inferior diastema is short, and when we add to this the 

 fact that P 3 is absent, it makes the diastema relatively shorter 

 still. There is a single mental foramen. 



In another specimen, No. 10412, the upward curvature of the 

 jaw at the anterior end is quite marked. The coronoid elevation 

 is small and located close to articular process. In other respects 

 this jaw resembles the type specimen closely. In one half of the 

 material the jaw is straight and the coronoid process is well for- 

 ward. This includes the type specimen. The other half of the 

 material shows the upward curvature of the jaw and posterior 

 position of the coronoid process. These differences are possibly 

 sexual or varietal. 



Cranium. — A skull (No. 10948) which may belong to this 

 species is about the same size as Smilodon neogaeus and S. neca- 

 tor, and conforms to the general form and shape of the skull in 

 these South American forms. In this specimen the left zygo- 

 matic arch is missing and on the right side the post glenoid and 

 mastoid processes are worn to a considerable extent, so that it is 

 impossible to tell whether these processes were fused, as it is in 

 the South American forms. The glenoid fossa is at about the 

 level of the roof of the mouth, allowing great freedom to the 

 lower jaw. The anterior border of the posterior nares is located 

 23 mm. behind the molars, a position quite a little posterior to 

 that seen in 8. floridanus, Leidy. The horizontal surfaces of 

 palatines and maxillaries forming the roof of the mouth have 

 well marked ridges running anteroposteriorly. Writing of the 

 type specimen of 8. floridanus, 4 Leidy says : ' ' The hard palate 



4 Trans. Wagner Free Instit. Sci. Philad., Vol. 2, pp. 15, 1889. 



