W. B. Scott — Some new forms of the Dinocerata. 307 



in the latter, which would almost certainly imply a similar 

 modification of the upper molars. Another reason against 

 such a reference comes from the presence of the large canine 

 tusk of the upper jaw, which, as we have already seen, had 

 probably not attained such dimensions in Bathyopsis. With 

 the exception of the last named genus, Elnchoceras is the small- 

 est known member of the group, the skull measuring only 

 about 22 inches in length. 



In the same locality, though at a somewhat higher level, was 

 found the large Uintatherium skull shown in fig. 4, which un- 

 doubtedly represents a new species of that genus, U. alticeps. 

 Nothing is more hazardous than making new species of the 

 Dinocerata, for, as every one who has studied them knows, 

 they are extraordinarily variable, and if judged by the usual 

 criteria almost every skull would constitute a distinct species. 

 However, by carefully comparing nearly forty skulls, I have 

 found that certain characters may be depended upon to deter- 

 mine the various species, not being subject to such apparently 

 capricious variation. Among these may be mentioned the 

 general shape of the skull, the position (not shape) of the 

 " horns," the shape of the occiput, the character of the tusk, 

 and the structure of the molar teeth. 



Examined with reference to these characters the skull shown 

 in fig. 4 is unquestionably distinct. It is one of the broad- 

 headed species, with remarkably high occiput, the parietal pro- 

 tuberance is in advance of the post-glenoid process. (I have 

 found the best method of exactly determining this point is to 

 connect the tip of the pre-maxilla with that of the post glenoid 

 process and erect perpendiculars on this line.) The molar 

 teeth are much as in U. lucare, but without tubercles on the 

 anterior cingulum ; there is a pair of small tubercles at the 

 entrance of valley of the last molar. The lunar has no facet for 

 the trapezoid. The great height of this skull, as compared 

 with its length, suggested the name alticeps. 



The value of the tubercles on the molar teeth as a specific 

 character has been questioned, but I am inclined to think that 

 considerable importance must be attached to them. For ex- 

 ample, the very large series of Palseosyops remains in the 

 Princeton Museum, ranging from species smaller than the sheep 

 up to those as large as the rhinoceros, show without exception 

 a small tubercle between the anterior cusps of the upper true 

 molars. The tubercles on the teeth of the Dinocerata show no 

 such constancy as this, it is true ; nevertheless they are suffi- 

 ciently constant to rank as species characters. 



These notes are preliminary to a much fuller account which 

 will shortly appear in a paper on the variations of the Dino- 

 cerata. 



Geological Museum, Princeton, N. J., Feb. 12, 1886. 



