BIG BADLANDS OF SOUTH DAKOTA. 469 



Elotherium ingens, "without paying much attention to the species," 

 as he has since told me. 



Elotherium ingens, as originally constituted,^ is a composite, com- 

 prising " fragments found in association with the fossils of Elo- 

 therium mortoni in the Mauvaises Terres, which appear too large to 

 belong to this species, even making allowance for a considerable 

 range in size." These were from the collection of Dr. Hayden, did 

 not pertain to a single individual and were from unknown horizons. 

 The first to be mentioned by Dr. Leidy^ is the " fore part of the 

 lower jaw, in advance of the second premolars," which therefore 

 becomes the type specimen of Elotherium {= Archceotherium) 

 ingens. In the light of what is at present known regarding the 

 larger entelodont species of the White River Oligocene, the various 

 fragments included by Leidy with the type of ingens are specifically 

 indeterminate, since the latter retains no teeth. 



A suggestion of Mr. Troxell's, in a personal letter, first called 

 my attention to the possibility that our Princeton specimen repre- 

 sented a new type and, on reviewing the subject, I agree with him 

 that the mandibular fragment figured by Leidy in front view on 

 Plate XXVII., Fig. lo, of the " Extinct Mammalian Fauna," copied 

 here on a smaller scale as Fig. 4, differs both in size and structure 

 from the corresponding part of the specimen monographed in detail 

 by Professor Scott,* for which I now propose the new name 

 Archccotherium scotti (Figs, i, 2, 3, 22), characterizing it as follows : 



I. Very long and thick dependent malar process directed down- 

 ward, forward and outward (the latter curvature probably intensi- 

 fied by crushing), with thin sinuous anterior margin and greatly 

 thickened, round-edged, club-like posterior distal end, projecting so 

 far below the anterior distal end of the process that the latter seems 

 to contract in breadth a second time after a minimum of 88 mm. and 

 a maximum of 114 mm. The greatest thickness of the enlarged 

 end is 46 mm. The outer face of the process is convex transversely 

 at the narrowest part, convex behind and flat in front at the widest 



3 J. Leidy, " The Extinct Mammalian Fauna of Dakota and Nebraska,'' 

 Jour. Acad. Nat. Set. Phila.. Vol. VIL, Second Series, p. 192, 1869. 



* " The Osteology of Elotherium," Trans. Am. Phil. Soc, Vol. XIX., pp. 

 273-324- Pis. XVII., XVIII., 1898. 



