238 



TEETIAET VERTEBEATA OF THE PATtM. 



to the loss of the posterior portion, the inner wall of the dental canal has heen crushed 

 in, and the anterior alveolus is incomplete. The symphysial surface («ym.) extends 

 back as far as the hinder border of pm. 2. The single alveoli of the incisors, the canine, 

 and the first premolar are empty; they are separated from one another and {r om pm. 2 

 by almost equal intervals of about 2-4 cm. Fm. 2 is a two-rooted tooth, compressed 

 and sharp-edged, with two accessory denticles on its posterior border ; pm. 3 is 

 represented by its two alveoli only ; pm. 4 is a large two-rooted tooth apparently 

 having three accessory denticles on both its anterior and posterior borders. The molars 

 are smaller teeth closely crowded together. In all, the anterior border is nearly 

 vertical and without denticulations, while the posterior border has two or perhaps three 

 accessory denticles in m. 1 and m. 2, and at least three in m. 3. The crowns of all the 



Text-fig. 77, 



nm..l. mi. . „ . „ 

 ' 771,2. m.3. 



Left ramus of mandible of Zcughdon osiris : A, frofti outer side ; B, from above. 



c, alveolus of canine ; i. 1-3, alveoli of the incisors ; m. 1-3, molars ; pm. 1-4, premolars or their alveoli ; 



sym., symphysis. ^ nat. size. 



teeth are somewhat obscured by a coating of gypsum. There are depressions for the 

 reception of the points of the upper teeth behind and rather to the outer side of the 

 alveoli of i. 3, c, pm. 1, and almost immediately behind the alveoli of pin. 2 and pm. 3. 

 The dimensions (in centimetres) of this specimen are given below ; those of the 

 specimens described by Dames and Stromer are placed in the second and third columns 

 for comparison : — 



Length from anterior end of jaw to anterior border of pm. 2 . . 24 



,, „_ border of pm. 2 to hinder border of in. 3 . 24-5 



Height of jaw beneath »'. 2 3'o 



i'm-2 6-7 



m.3 11 app. 



Length of the syinph3'sial surface 28 



