214 



ON THE EXTINCT MAMMALIA OF 



The hard palate between the position of the canine and incisive alveoli is deeply 

 arched. The anterior palatine foramina are comparatively small, about the third of 

 an inch in diameter, and lead into defined grooves descending internal to the position 

 of the first incisors. 



Inferior maxilla. — Small fragments of the lower jaw, with mutilated condyles, 

 present these as having nearly the same relative position and shape as in Rhino- 

 ceros. They are transverse, clavate convexities, with the narrow extremity internal. 

 The coronoid process, broken away in the specimens, starts at its root about an 

 inch in advance of the condyle. The notch separating the two is broad and 

 shallow. 



The specimens under examination are too imperfect to determine the form of the 

 back part of the lower jaw. The posterior border appears as if it had curved upward 

 from the base as in Rhinoceros. 



The outer vertical sides of Dr. Front's specimens, described in the Ancient Fauna 

 of Nebraska (figure 1, plate xvi of that work), measure below the middle of the last 

 molar five and a half inches in depth ; and the convex base of the same, below the 

 first true molar, is two and a quarter inches in thickness. 



A fragment of a lower jaw, belonging to Prof Hall's collection, has a depth of five 

 inches below the first true molar, and a thickness of two and a half inches. 



The base of the jaw is antero-posteriorly convex, as in Anoplotherium and Rhinoce- 

 ros. The chin presents a broad sloping surface as in the latter genus. Two mental 

 foramina are situated below the position of the second premolar tooth. 



Measurements of the jaws and teeth of Titanotherium derived from different 

 specimens are as follow : 



1. Measurements of the upper jaw and teeth from the specimen in Prof Hall's 

 collection; one series of the teeth being represented in figures 1, 2, plate XXIV : 



Width of space between canines occupied by incisors, 



From incisive alveoli to entrance of nasal orifice, 



Width of face outside of canine alveoli, 



Distance from incisive alveoli to back of last molar, 



Length of series of the molar teeth. 



Length of true molar series. 



Inch. Lin. 



Diameter of last true molar, antero-posteriorly, 3 10; 



Diameter of second " " 3 3 



Diameter of first " " 2 4 



Diameter of last premolar, " 17 





Inch 



Lin 





2 



3 





3 



4 





4 



2 





17 







14 







9 







Inch. 



Lin. 



transversely, 



3 

 3 



5 



5 



i( 



2 



10 



i( 



2 



5 



