MEGACEROPS TYLERI 445 



Specifically the creature most nearly resembles Megacerops 

 bicornutus Osborn and Megacerops (Di plod onus) am plus Marsh, 

 having certain characters suggestive of each; but there are enough 

 important differences to render it distinct and to warrant the erection 

 of a new species for its reception. 



Megacerops tyleri sp. nov. 



Type No. 327 of the Amherst College Zoological Collection. Horns well in 

 front of orbits, directed somewhat forward and outward, an elongate oval in basal 

 section with the long axes in line, rounded oval at the summit. Hornlets quite 

 conspicuous, on the inner face of the horns midway between the base and summit. 

 Connecting-crest low and inconspicuous. Nasals broad, well rounded in front, 

 and but slightly arched beneath. Zygomata expanded and deep, with a well- 

 rounded outer face. Dentition : Superior incisors represented by the deep and 

 well-defined median alveoli, and by the lateral teeth which remain in place, and 

 which have hemispherical crowns which show little sign of wear. The canines are 

 lanceolate, with a well-developed postero-internal cingulum. There is a short 

 diastema in front of, and a longer one behind, the canine. Premolars with a 

 smooth internal cingulum, less pronounced in the middle of the tooth, and with 

 no external cingulum. The deuterocone is well developed, while the tetartocone, 

 especially of premolar four, is inconspicuous. 



The jaw is deep and robust, with the alveoli of two incisors, probably of the 

 second and third, deep and distinct. There is no space between the lateral 

 incisors and the canine, though between the two median alveoli a considerable 

 gap occurs. There seems to have been a small diastema behind the lower canines, 

 which are lanceolate, though with a less prominent cingulum, and not so strongly 

 recurved as the upper ones. 



COMPARISON WITH ALLIED SPECIES 



The form under consideration resembles most closely Megacerops 

 (Diploclonus) amplus Marsh and M. bicornutus Osborn, agreeing 

 with both in the possession of hornlets, and with one or the other in 

 minor characters, but differing in general contour of the skull and 

 horns. The table on next page shows the main points of resemblance 

 or contrast in the three species. 



Professor Osborn, in his description of M. bicornutus, mentions 

 as a cotype skull No. 1081 of the American Museum — a specimen 

 with a somewhat checkered career, as it was first described and 

 figured by Osborn in the American Museum Bulletin 1 as " Titano- 



1 Vol. VIII, Art. IX, pp. 176, 177. 



