376 E. L. Troxell — Entelodonts in Marsh Collection. 



Additional measurements have been taken to supple- 

 ment the list of Marsh, as follows : 



mm. 



Length of malar process below the orbit 202.6 



Width of process at narrowest point 52.0 



Greatest width distal 62.0 



Diameter of thinnest part 22.0 



Length of anterior process of temporal, measured from edge of glenoid 

 cavity 103.0 



The holotype is known by the complete zygomatic arch 

 (fig. 9), one humerus and both right and left radius and 

 ulna; of each of these a portion of the shaft is missing. 

 There is also the proximal end of the other humerus and 

 of a tibia ; one fore foot is nearly complete and there are 

 other foot bones, including a part of the pes ; there exist 

 also a few fragments of vertebrae and ribs. 



The zygomatic arch, the first ever described, with the 

 long slender process from the malar, is unusually inter- 

 esting. The width of the process is only about one-fourth 

 of its length ; it hangs wholly out of line of, and behind the 

 orbit, and the tip which curves slightly backward is thick- 

 ened and knob-like. The anterior edge of the blade is 

 thin, extended forward, and rounded inward slightly. In 

 its downward course the first third is thicker and forms an 

 arch concave inward; through the center it narrows 

 slightly and completes a sigmoid curve by thickening out- 

 ward at the rounded tip. 



The sutural surface, which comes in contact with the 

 temporal, forms a notch, then a long backward extension 

 in a nearly flat plane. The inner edge of this plane is 

 bevelled off at an angle of about 50°. The slender pro- 

 cess from the temporal, which fits into the notch on the 

 jugal just described, extends upward and forward, but 

 curves sharply inward and ends in a blunt rounded point. 



The border of the glenoid fossa is not "cut away" to 

 permit the tip of the jugal to form a part of the actual sur- 

 face of the condyle. The fossa itself is not high an- 

 teriorly, and the edges are rounded, not sharp. It is not 

 long in lateral extent, as compared to some other species, 

 and the whole surface seems to be more nearly symmetri- 

 cal, not extended diagonally. Above there is a slight de- 

 pression posteriorly, instead of on the outer surface as in 

 A. marshi (fig. 10). 



The canal of the external ear is beautifully shown, un- 

 covered by the absence of the tympanic between the exoc- 



