Hoplophoneus occidentalis. 



BV E. S. RIGGS. 



(With Plate I.) 

 [Sul)niittecl to tlie FucuUy of Kansas University as a thesis for tlie degree of A. M.] 



The species Hoploplioncus occidentalis Leidy is based upon a 

 fragment of a mandible from the White River Beds, described in 

 Leidy's Extinct Mammalian Fauna of Dakota and Nebraska. It 

 shows the lower molar dentition to be P. M.t^, M.^; but of these 

 the crowns of the third premolar and the sectorial are lost, as are 

 both extremities of the mandible, so that even the size of the 

 animal could only be approximated. Nothing more was ascribed 

 to this species until 1894, when Osborn and Wortman referred two 

 specimens to it*. In 1895 Dr. Williston published in this Quar- 

 terly! a preliminary description of two specimens of a large sabre- 

 toothed cat obtained during the previous summer in the White 

 River Beds of South Dakota by the University Geological Expedi- 

 tion, to which he gave the name of Diiiotomiiis atrox. In January, 

 i8g6,;{; Mr. Geo. i. Adams determined a mandible (No. 1407 

 Amer. Mus. ) as Hoplophoneus occidentalis and described the smaller 

 form of Osborn and Wortman as a distinct species, suggesting also 

 that D. atrox was a synonym of H. occidentalis, since it agreed 

 with the American Museum specimen. 



In his preliminary description of D. atrox, Dr. Williston, de- 

 scribing a complete tooth, characterized the inferior sectorial as 

 follows: "Molar much as in the cat, save there is a well-developed 

 internal posterior tubercle and the heel is rudimentary." An 

 accompanying plate, although concealing the anterior portion of 

 this tooth, represented it as described. Nevertheless, Mr. Adams 

 in reproducing Dr. Williston's drawing for comparison with the 

 American Museum specimen, has taken the liberty to reconstruct 

 this tooth so as to show a prominent heel and no postero-internal 

 cusp, and then states that the two specimens agree. Again, in the 

 American Journal of Science for June, 1896, Mr. Adams reproduces 



*Bul]etin of the American Musoum of Natural History, 

 tlvansas University Quarterly, Vol. Ill, No. 3. 

 $The American Naturalist, .January, 18i)(), 



{'■it) KAN. UNIV. QUAR., VOI.. V, NO. 1, JULY, 18%. 



