KIGGS: HOPLOPHONEUS OCCIDENTALIS. 49 



The astragular surface is, as in H. robust iis, less deeply grooved 

 and is placed more obliquely to the shaft than in recent cats. The 

 antero-external border extends but little below the articular surface. 



Of the fibula only the extremities remain. These indicate a 

 stronger bone than that of H. robustus. The proximal end articu- 

 lates with the tibia by a well-marked oval facet. The outer sur- 

 face is roughened for ligamentary or muscular attachments. There 

 is only a trace of a groove on the outer surface, instead of the 

 deep concavity found in H. robustus. The distal end, as in the 

 last-named species, is very unlike that of recent cats. It is nar- 

 rower but thicker than the head and is roughly triangular in sec- 

 tion. The internal surface bears at its lower anterior border a 

 convex articulating facet for the astragalus which curves half way 

 around the lower end. The posterior surface stands at a right 

 angle with the last, and is almost as broad. There is a broad, 

 shallow, peroneal groove at the inner side of the posterior tuber- 

 osity of the malleolus. Th<=' tendinous depression on the external 

 surface is less marked than in the recent cats. 



The foot is short and weak in the metatarsal region, as is true of 

 all the early cats. The calcaneum is not more than two-thirds as 

 large proportionally as that of the lion, and does not extend dis- 

 tally as far as the astragalus. The external process extends back- 

 ward beyond the anterior margin of the superior articulating 

 surface. Back of this and near the upper surface is a deep fossa. 

 The sustentaculum is situated near the anterior border, opposite 

 the external process and has a broad, shallow groove at its base. 

 The anterior surface is quite concave; the articulating surface for 

 the astragalus does not turn inward posteriorly, as in the recent cats. 



The a-strag-alus has a short, constricted neck, and a well-rounded 

 head, but is markedly compressed vertically. The superior surface 

 is but slightly concave laterally, corresponding to the slight convex- 

 it}' of the tibial surface, and does not extend to the posterior border 

 as in recent cats. This does not permit of as great an angle 

 between the foot and the tibia, and bears evidence of more planti- 

 grade affinities. The head is less deflected from the antero- 

 posterior axis than in the lion. There is no articulation with the 

 cuboid, as is the case in Dinictis. The facet for articulation with 

 the sustentaculum is long and deeply notched posteriorly. The 

 posterior end is grooved for the tendon of X\\^ flexor longus hallucis. 

 The groove between the inferior articulating surfaces is straight, 

 and ends abruptly in a deep fossa. 



