152 



ON THE EXTINCT MAMMALIA OF 



The post-coronoid process springs from a relatively wider lamina than in the Camel 

 or Lama. It is not situated so high as in either of the latter; its point, which is 

 thick, strong, and somewhat bent inwardly, rising but little above the level of the 

 masticating surfaces of the teeth. 



The condyle is situated at a lower level than in the Camel or Lama, and in its 

 form resembles that of the latter, but differs from that of either in its anterior portion 

 having a strong inclination inwardly and its posterior portion being quite vertical. 



The entrance of the dental canal is about opposite the general level of the alveolar 

 border, and is about half way between the posterior molar tooth and the post-condyl- 

 oid notch. 



The molars and last premolar, figures 5, 6, d to g, closely r-esemble those of the 

 preceding species, as they do likewise the corresponding teeth of the Camel and 

 Lama. 



The second and third molars retain the remains of the enameled intervals of the 

 external and internal lobes, seen as crescentoid and ellipsoid pits upon the worn tritu- 

 rating surfaces, fig\ire 6,/, g. Li the first molar and the premolar in advance the tritu- 

 rating surfaces present broad surfaces of dentine bordered with enamel, figure 

 6, d, e. 



In advance of the last premolar the jaw fragment retains the pair of sockets of the 

 third premolar. 



The measurements of the specimen compared with those of the Lama and Camel 

 are as follow : 



P. occid's. Lama. CameL 



Depth of lower jaw below last molar, 



Thickness of jaw below " 



Breadth from last molar obliquely to techuical angle, 



Height from level of base to eud of post-coronoid process, 



Height from base to condyle, 



Distance from last molar to end of post-coronoid process, . 



Breadth of ramus ou level with bottom of post-condyloid notch, 



lireadth of condyle, .... 



Length of series of true molars and last premolar. 



Length of series of true molars, 



Antero-posterior diameter of last premolar, 



" " first molar, 



" " second do. 



last do. . 



Inch. Lin. 



2 3 

 1 4 



2. A fragment of the fore part of the left side of a lower jaw, containing the last 

 premolar entire, with portions of the other premolars and the first molar, and a por- 

 tion of the alveolus for a canine tooth. 



The specimen belonged to an individual not quite so aged as the former, as indi- 

 cated by the less worn condition of the last premolar tooth. The jaw fragment is of 

 less proportionate depth than the corresponding part of the former appears to have 



