LOXOLOPHODON AND UINTATHERIUM. 



31 



is marked at the top by a very slight ridge. The posterior lobe comes to an 

 obtuse point about two thirds the height of the anterior. The inner surface of 

 the tooth has a flat, slightly raised, and faintly serrate margin. The second and 

 lateral incisors decrease in size regularly with the same characters as the above, 

 except that the posterior lobe of the lateral tooth is relatively higher. In the 

 canine the cleft at the head of the valley has disappeared, and consequently there 

 is a deep single valley. The fangs throughout the series are long, and stout; 

 they arch forwards slightly, and decrease in size with the crowns. 



Comparative Measurements of the Teeth of the Lower Jaw. 



Lox. Uinta. 



M. M. 



Entire length of molar series (6 inches) 166 .... 



Length of the molar series 094 • • • • 



Fore-and-aft diameter of last true molar 047 



Transverse diameter of same 036 026 



Heigot of crown of same 030 -023 



Fore-and-aft diameter of first premolar 023 .... 



Transverse diameter of same oi9 .... 



Height of crown of same 022 .... 



Length of canine-incisor series 140 . • • . 



Width of median incisor 019 .... 



Length of same 041 .... 



Height of crown of same 037 .... 



Width of external lobe of same 026 .... 



Width of internal lobe of same 015 .... 



Length of fang of same 060 .... 



Width of canine 015 .... 



Length of same 036 .... 



The measurements of the Uintatherium molars are from specimens which 

 Dr. Leidy kindly lent us, and which have been described in full.' They corre- 

 spond closely, except in size, to those of Loxolophodon. 



General Characters of the Teeth. 



The characters of the teeth sustain th.e inference, drawn from the study 

 of the limbs and skull, of the aberrant position of this group, and of their prob- 

 able origin from a common stock with the Coryphodon group. The latter genus 

 displays a marked divergence towards the Perissodactyle ungulate type, while 

 the Dinocerata with marked ungulate characters in their dentition show an 

 advance along an independent line. Coryphodon in the premolar series of the 

 lower jaw presents curved inward-opening crests, while the molar series are 

 marked by simple transverse crests, as in the Tapir. The upper teeth, accord- 

 ing to Cope, present slight divergence from the ordinary Perissodactyle type. 



' Cont. from the E. M. Museum; Princeton College, No. i, Sept. 1st, 1878, page 71. 



