June, 1912. New Titanotheres — Riggs. 31 



Dolichorhinus Hatcher 



Type species (D. cornutus Osborn) hyognalhus S. & O. 

 Range: Upper Bridger, Washakie and Lower Uintah. 

 Original characterization:* "Distinguished from Manleoceras and 

 Telmatherium by the reduced number of incisors, presence of 

 incipient horns, presence of infra-orbital shelf and the position 

 of posterior nares." 

 Further knowledge of the genus has proved that the reduction in 

 the number of lower incisors is not constant. The genus may now be 

 characterized as follows: 



Middle Eocene titanotheres progressively dolichocephalic, nasals 

 elongate and laterally infolded, cranial region strongly convex, 

 incipient horn-cores above the orbits, a shelf -like infra-orbital 

 process, occiput broad and low, condyles broad. Dentition 

 complete, premolars relatively progressive, first pair of upper 

 incisors separated by median diastema, posterior nares opening 

 back of last molars. f Vertebral formula: Cerv. 7, Dors. 17, 

 Lumb. 4, Sac. 4. 

 The elongate skull, 440-600 mm., with deeply recessed nasals and 

 wide sagittal area strongly convex in the cranial region, everywhere 

 distinguishes this genus. The specimens examined by the writer all 

 bear evidence of a recession of the posterior nares by a secondary bridg- 

 ing of the palate. The nasals are laterally recessed to a point over the 

 first molar. They may be expanded in the distal third or uniformly 

 tapering. The infra-orbital process is thickened and rugose at the 

 extremity. The median diastema between the first pair of incisors 

 is a notch-like recess at the suture, varying from ten to fifteen milli- 

 meters in breadth. The upper canines differ considerably in size and . 

 in direction, varying from procumbent to recurved types. The grind- 

 ing teeth are longer in the crowns than in any of the other Lower Uintah 

 titanotheres. The last molar bears a more or less developed hypocone. 

 The post-glenoid processes are massive and elongate anterio-posteriorly. 



D. cornutus% Osborn. 



Type specimen, No. 1851 Amer. Mus. 



Type locality: Uintah B. 



Synonym J of D. hyognalhus S. & O. from Washakie B. 



* Amer. Nat,, Vol. XXIX, p. 1090, 1895. 



t D. heterodon offers a possible exception to this rule. 



§ Bull. Amer. Mus., Vol. VII, p. 90, 1895. 



% Bull. Amer. Mus., Vol. XXIV, p. 611, 1908. 



