1887 ] ^Oi [Scott and Osborn. 



ever, to have been a diastema between the canine and first premolar, 

 though this is not certain, which is not the case in Uelaletes. 



The species is rather small, somewhat larger than Helaletea laiidens of 

 the Bridger. 



Measurements. 



M. 



Length upper molar series 048 



First molar, antero-posterior diameter (?) 015 



" " transverse " (?) 015 



Second" anteroposterior " 015 



" " transverse " 014 



Third " antero-posterior " 016 



" " transverse " 018 



Third upper premolar, antero posterior diameter 013 



" " " transverse " 



Third lower molar, antero-posterior " 033 



" " " transverse " Oil 



The study of this genus shows that Hyraehyus and Desmatotherium 

 cannot be placed in the direct line of tapir ancestry, as we were formerly 

 disposed to believe. Much more probably this line has come down 

 through the genera with trilobed last lower molar, and it is noteworthy 

 that the tapiroids from the White River beds have the third lobe or talon 

 present, though less distinctly marked. These animals have been 

 described by Dr. Leidy,* under the name of Lophiodon, from which 

 genus the known specimens do not appreciably differ. But, as Dr. Leidy 

 lias suggested, they probably belong to a very different genus, which, 

 when better known, will in all likelihood be found to be intermediate in 

 character between Isectolophus of the Uinta and Tapiravus of the Loup 

 Fork. According to this view the series of genera would be : Helaletes, 

 Isectolophus, the White River genus, Tapiravus and Tapirus. 



Amynodon ]\Iarsh {Syn. ? Orthocynodon, nobis). — Professor Marsh's 

 description of this genus is as follows :f "The skull is intermediate in 

 form between tllat of a Tapir and a Rhinoceros, but the molar teeth are 

 entirely of the latter type. The premolars are all unlike the molars, and 

 the canines above and below are very large. The incisors are small and 

 the inner one in each jaw is lost in the present adult animal. The lower 

 canines are placed nearly horizontal, and, taken in connection with the 

 rest of the anterior dentition, they prove conclusively that the large lower 

 teeth usually regarded as incisors in Aceratherium * * * are really 

 canines." The number of digits is stated to be iv-iii. This description 

 is erroneous in most of the particulars, owing to the fact that it was drawn 

 up before the type specimen had been removed from the matrix and put 

 together, and in this way, even after examining the type ourselves, as 



* Ext. Mamm. Faun, of Dak. and Neb., p. 239. 



t Am. Journ. Sei. and Arts, Third Ser., Vol. xiv, p. 251. 



