Peterson: Material Discovered in I^inta Basin. 127 



Superfamily RHINOCEROTOIDEA. 



Family HYRACODONTID.4^. 



Subfamily HYRACHYIN.4^. 



Genus Desmatotherium Scott. 



39. Desmatotherium guyotii Scott (Plate XLIV, Fig. 6). 



Contributions from The E. M. Museum, Princeton, N. J., Bull. No. 3, 1883, p. 

 46, Pl.'.VIII, Figs. 1-3. 



Type: Upper jaws, No. 10166, Princeton Museum Catalogue. 



Horizon: Eocene Formation (Bridger Beds). 



Locality: Henry's Fork, Wyoming. 



Generic Characters: Professor Scott defines the genus as follows: 

 "Lophiodonts closely allied to Ilyrachyiis, having the molar teeth 

 constructed exactly as in that genus, but differing from it in the pattern 

 of the third and fourth upper premolars, which have two internal cusps 

 instead of one. Dental formula: ^ c. 5^^ Pm. -^fy M -^." 



In his specific determination Scott states that the postero-internal 

 cusp of P- "is very small and situated somewhat exterior to the 

 antero-internal cusp." His illustration (/. c, PI. VHI, Fig. 3) also 

 appears to agree with this statement. Both are erroneous and clearly 

 a mistake, since his detailed description of P- apparently agrees better 

 with the actual type specimen. Upon the reexamination of the 

 specimen (See PI. XLIV, Fig. 6) it is clear that the tetartocone is on a 

 more nearly even antero-posterior line with the deuterocone, and 

 that the cusp represented in Professor Scott's illustration is an en- 

 largement, or an intermediate tubercle located on the posterior cross- 

 crest. The tetartocone is very much ground down by the opposition 

 of the inferior tooth. "^ The true condition is better shown on P^ of 

 the left side, which is completely preserved, and from which the draw- 

 ing represented by the present illustration is partly restored. 



Scott states (/. c, p. 48) that the true molars of Desmatotherium 

 are, with few minor differences, very similar to those in Hyrachyiis, 

 and the matter here needs no further discussion, except to say that 

 these two genera are indeed very closely related. 



Comparison and Relationship. 

 With regard to the taxonomic position of Desmatotherium I am 

 strongly impressed with the idea that the genus is not directly ances- 



"■ It is possible that this tubercle was broken off and healed over before the 

 death of the animal. 



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