BIG BADLANDS OF SOUTH DAKOTA. 473 



" turtle-oreodon layer," lower Oreodon beds, probably in Sec. 5, 

 T. 4 S., R. 13 E., Black Hills meridian, near the headwaters of one 

 of the most easterly branches of Indian Creek, west of Hart Moun- 

 tain, in Pennington County. 



Fig. 5. ArchcEotheriutn wanlessi sp. nov. Holotype, No. 12522. Left side 

 of the skull and lower jaw, one sixth natural size. Drawn from photograph 

 and the specimen. 



This new form which it is proposed to name after its discoverer, 

 Mr. Wanless, is well differentiated from all of the larger White 

 River entelodonts by the following characters, believed to be specific : 



I. Marked peculiarities of the dependent malar processes. 

 These are short, wide and thin, directed outward, downward and 

 forward, and vastly shorter than in either A. crassmn or A. marshi, 

 which approach No. 12522 most closely in size. The antero-distal 

 margin is 4-6 mm. thick, is slightly everted and is almost at right 

 angles to the distal border which gradually thickens backward, due 

 to a broad swelling whose center is about 30 mm. above the distal 

 end of the process, where a maximum thickness of 19 mm. is at- 

 tained. From here it thins out in all directions, but less rapidly so 

 proximally. At its greatest antero-posterior expansion the process 

 is 80 mm. wide and but 10 mm. less at its narrowest part. Its front 

 margin is concave and well back of a line drawn through the pos- 

 terior border of the orbit. From the upper edge of the temporal 

 bar the outer face of the malar process is slightly sigmoid in longi- 



