226 



ON THE EXTINCT MAMMALIA OF 



end of the snout leads to the suspicion that a nasal weapon of the same kind was also 

 absent. 



Measurements derived from tlie skull of B. occidentalis of Dr. Owen's collection are 

 as follow : 



Estimated length of the skull when entire, about . 

 Estimated breadth of the inion at the mastoids, 

 Length from occiput to front of first molar, . 

 Breadth at zygomatic arches, 

 Distance between tips of post-glenoid processes, 

 Length of temporal fossa, fore and aft, 

 Depth " « « , , 



Greatest breadth at supra-orbital processes, . 

 Distance from ant-orbital margin to lateral nasal notch, 

 Breadth of face at last molar alveoli, 

 Breadth of face at first molar alveoli. 

 Length of upper molar series. 

 Length of series of the three upper true molars. 

 Diameters of molars : 



Lines. 



Inches. 



18 



5 

 16i 



8 



8^ 



4 



7 



4J 



5 



21 



7i 



4 



Lines. 



First premolar, 



antero 



-posterior, 



9h; 



transverse, 



9* 



Second " 





i( 



Hi 





12* 



Third " 





li 



12* 





16 



Fourth " 





a 



13* 





17* 



First true molar. 





ct 



16* 





18 



Second " 





ec 



19 





20 



Last " 





ee 



19* 





19 



Measurements derived from three specimens of lower jaws of B. occidentalis, 

 including that of Prof Hall's collection, are as follow : 



From back of last molar to front of jncisors. 



Depth of jaw below middle of last molar. 



Hiatus between molars and incisors, 



Length of molar series of six. 



Breadth of incisive space of both sides, . 



Depth of symphysis. 



Breadth of chin below hiatus of the teeth midway. 



Breadth of first lower molar, 



Lines. 



Lines. 



Line 



108 



• 





25 



32 



28 



22 







73 



78 



92 



20 







34 







18 







9 





11 



