Platygontjs. 





D1COTYLE8. 



Adult. 



Young. 



Adult. 



82 mm. 



84 



mm. 



94 mm. 



36 " 



37 



tt 



38 " 



78 " 



73 



tt 



65 " 



36 " 



35 



« 



36 " 



78 " 



82 



it 



83 " 



52 " 



54 



tt 



31 " 



24 " 



23 



tt 



30 " 



INSTITUTE OF SCIENCE, PHILADELPHIA. 47 



Height of mandible at coronoid process, 

 Depth of mandible below the premolars, 

 Depth obliquely at the symphysis, 

 Width at the canine alveoli, 

 Length of the lower molar series, . 

 Length of the hiatus in advance. 

 Transverse diameter of the condyle, 



Comparative measurements of the molar teeth in two adult skulls and 

 a young skull of Platygonus compressus. In the former the teeth occupy 

 their functional position and all are worn. In the young skull the perma- 

 nent premolars and the last true molar had not protruded and are there- 

 fore unworn. Measurements in millimetres : 



Adult. Young. 



Upper teeth. Lower teeth. Upper. Lower. 



Length of the molar series, 74 mm. 74 mm. 80 mm. 80 mm. 83 mm. 

 " ofthe true molar series, 45 " 



Length of the premolar 



series, . . . 29 " 



Fore and aft diam. last true 



molar, . . . 19 " 



Transverse diam. last true 



molar, . . . 14.5 " 



Fore and aft diam. second 



true molar, . . . 15 " 



Transverse diam. second 



true molar, . . 15 " 



Fore and aft diam. first true 



molar, . . . 12 " 



Transverse diam. first true 



molar, . . . 12 " 



Fore and aft diam. last pre- 

 molar, . . . 10 " 



Transverse diam. last pre- 

 molar, . . . 12.5" 



Fore and aft diam. second 



premolar, . . .10" 



Transverse diam. second 



premolar, . . 11 " n " 8 " 11.5 " 9 " 



Fore and aft diam. first pre- 

 molar, . . .9-5" 9 " 9-5" 9-5" 9 " 



Transverse diam. first pre- 

 molar, ... 9.5 " 9-5 " 8 " 9 " 8 " 



46 



tt 



49 " 



50 



a 



51.5 " 



28 



tt 



29.5 " 



31 



a 



31 " 



17 



it 



22 " 



20.5 



tt 



22 " 



13 



a 



12 " 



14-5 



it 



12 " 



16 



« 



15.5" 



16 



it 



17 " 



15 



it 



12 " 



15 



a 



II " 



14 



tt 



13 " 



14 



ti 



14.5 " 



13 



it 



10.5 " 



12 



it 



10.5 " 



II 



it 



II " 



10 



tt 



II.5" 



13 



1) 



9-5" 



II 



if 



10 " 



10 



it 



II " 



II 



tt 



10 " 



