PLATE CLIII 



Type Skull of Megacerops btjcco and Jaw of Brontops? 

 Plate prepared under the direction of Professor Cope. One-third natural size. (See p. 544) 



A., Megacerops {" Symhorodon") bucco, type (Am. Mus. 6345a), Horsetail Creek, northeastern Colorado, Chadron formation. The 

 skull is poorly preserved and is vertically crushed, thus rendering its specific affinities somewhat uncertain. The figure is 

 rather unsatisfactory, especially in the form of the horns and nasals. Of the two cotype skulls referred to in Cope's original 

 description of Symborodon bucco this one is taken as the leototype, because upon it were based nearly all the measurements 

 and specific characters Usted by Cope. 



B, Lower jaw of Brontops? (Am. Mus. 6345b), Horsetail Creek, northeastern Colorado, Chadron formation. Placed by Cope 

 ■nith the type skull of Megacerops {"Symborodon") bucco but probably pertains to the genus Brontops. It differs from the 

 supposed true Megacerops figured in Plate CLVIII, A, in general contour and in the possession of well-developed external 

 cingula on the cheek teeth. 



G, Undetermined jaw fragment from Colorado, referred by Cope to Megacerops {"Symborodon") bucco. It may pertain to Brontops. 

 (See PL CLVIII, B.) 



