214 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



Cotypes. — Skull (Am. Mus. 6355) lacking all the 

 teeth except m^; Am. Mus. 6356, anterior-inferior por- 

 tion of skull, including horns, nasals, right zygoma, 

 and teeth. Of these two cotypes we may regard No. 

 6355 as the lectotype. (See fig. 172.) 



Specific characters (summarized from Cope). — A 

 strong basal cingulum, on the inner side of the pre- 

 molars, which is continued in a less prominent form 



Present determination. — This is a valid 

 described on page 528, referable to Menodus. 



species, 



Brontotherium ingens Marsh, 1873 



Cf. Menodus giganteus, this monograph, page 530 



Original reference. — Am. Jour. Sci., 3d ser., vol. 7, 

 pp. 85, 86, pis. 1, 2, January, 1874; "published Dec. 

 30, 1873" (Marsh, 1874.1). 



■"-^fS^ ^ 





Figure 169. — Type (lectotype) skull of Symborodon bucco 

 Am. Mus. 6345. After Cope, 1874. One-ninth natural size. The mandible in the upper figure probably does not belong with the skull. 



between the bases of the cones of the molars. Bases 

 of cones of premolars strongly plicate. Horns tri- 

 quetrous, dii-ected outward and upward. Squamosals 

 not expanded, nasals elongate transversely plane. 



Etymology. — rpis, three; yuvla, angle; Kepas, horn; 

 in allusion to the three-sided section of the horn. 



Subsequent reference. — Marsh, The principal char- 

 acters of the Brontotheridae, p. 335, text figs. 1, 2, 

 pis. 10, 11, 1876 (Marsh, 1876.1). 



Type locality and geologic horizon. — Colorado; Chad- 

 ron formation {Titanotherium zone); exact locality 

 and level not recorded. 



