438 E.'L. Troxell — Entelodonts in Marsh Collection. 



not to mention the triturating surfaces. From the food 

 or the tongue itself, the inner sides are worn most smooth, 

 but the outer surfaces are also polished, to a less degree, 

 by the food and cheek muscles. It is a general rule that 

 the more aged the teeth, the smoother the enamel, espe- 

 cially on the inner side. 



P 2 (see fig. 17) is rather stout, directed slightly for- 

 ward, is convex on both sides, especially exteriorly, has 

 its slopes rounded not angular (cf. M. zygomaticus, fig. 

 16), is not pitted, has a weak cingulum, both posterior and 

 anterior, and only two ridges running to the apex of the 

 cone. It is wide anterior to the cone but narrows rapidly 

 at the end beyond. 



P 3 had not fully erupted, but has been uncovered in 

 preparation. It is smoothly oval, has a fine sharp ridge 

 from the cone on the postero-exterior corner, and a rela- 

 tively smooth heel. The cingula are very faint or entirely 

 lacking. 



Premolar four has its outer and back sides square and 

 straight and the inner side rounded, but, unlike M. zygo- 

 matics, and like most species of Archceotherium, the 

 front side is indented. The deuterocone seems to be 

 small, but the tooth is considerably wider than long, 39 X 

 35 mm. The cingulum, which is especially strong pos- 

 teriorly, does not appear on the outer and inner sides. 

 The tooth is rounded rather than angular. 



The molariform, deciduous premolar four still covers 

 the permanent tooth on the left side. Its cusp arrange- 

 ment is faithfully patterned after the first true molar. 



The first molar shows a strong protoconule and a strong 

 metaconule well separated from the hypocone. There is 

 also a hypostyle continuous with the cingulum and the 

 hypocone. Though the tooth is subquadrate, the long 

 slope of the inner face gives it a peculiar appearance and 

 increases the transverse diameter greatly, the width being 

 45.5 mm. and the length 40 mm. ; the outer side is bilobed 

 and of these, that of the metacone extends farthest out. 



The second upper molar is also subquadrate but is 

 wider in front and is rounded behin4. The hypocone and 

 metaconule are almost united. The cusps are all nearly 

 equal in size, but the base of the protocone is rather wide. 

 A small cusp on the posterior edge may be considered as 

 a hypostyle. 



M 3 is not erupted but its surface has been plainly ex- 



