352 SCOTT. [Vol. XI. 



cuneiforms, is L-shapcd, occupying the dorsal and tibial sides 

 of the bone. The surface for the entocuneiform is relatively 

 very large in the dorso-plantar direction, but very narrow trans- 

 versely ; it is placed on a downward projection from the distal 

 face of the navicular and stands at a considerably lower level 

 than the facet for the compound bone. The posterior hook 

 from the plantar side of the navicular, which is so conspicuous 

 in the oreodonts, is absent in Protoceras. 



As in nearly all known selenodonts, recent or fossil, the meso- 

 and ectocuneiforms are indistinguishably fused together. This 

 occurs even in the oldest known American artiodactyl, Trigono- 

 lestes, of the Wasatch. The compound element thus formed 

 is nearly as broad as the cuboid, and of much greater vertical 

 height relatively than in the recent Pecora ; it articulates with 

 the second and third metatarsals. 



The entocuneiform is much larger proportionately than in 

 the recent Pecora or Tragulina ; its principal dimension is the 

 vertical one and it forms a high, deep, and compressed plate, 

 which has numerous connections. Proximally it articulates 

 with the navicular and distally with the head of the second 

 metatarsal, also with the projection from the plantar side of 

 the third. In the Pecora this latter articulation does not exist. 



The Metatarstis (PI. XXII, Fig. i8) consists of four ele- 

 ments, two of which (mt. II and V) are splint bones and two 

 (III and IV) are large functional digits. In one of the speci- 

 mens described by Osborn and Wortman the second metatarsal 

 is more than one-third the length of the functional pair, but 

 ordinarily it is much shorter and forms a narrow compressed 

 splint, tapering to a point inferiorly. It articulates with the 

 mesocuneiform portion of the compound element and by a 

 long truncated surface with the entocuneiform. 



The third metatarsal is very much larger, longer, and heavier 

 than the corresponding metacarpal. The head bears a large, 

 somewhat concave facet for the compound cuneiform ; the 

 posterior hook-like projection, which in existing Pecora has 

 become rudimentary, is very large and prominent and bears an 

 oblique facet for the entocuneiform, as is also the case in 

 Oreodofi. On the tibial side of the head is a deep fossa in 



