644 THE WASATCH FAUNA. 



nate with the apex slightly curved inwards. Its anterior and interior faces 

 are abruptly contracted, the narrowing of the former commencing at a 

 curved transverse ridge which is on a level with the head of the femur. 

 The anterior convexity of the shaft commences at this transverse ridge. The 

 third trochanter is rather prominent, and is recurved. The rotular groove 

 is rather narrow and deep, and its smooth surface is continuous with that 

 of the condyles. There is scarcely a trace of the fossa so marked on the 

 inferior part of the posterior side of the shaft in Anchitheriiim. A part of 

 the shaft above the third trochanter of this femur is lost, so that full meas- 

 urements cannot be given. 



The tibia is rather slender. The internal femoral face is wider antero- 

 posteriorly, and the external face is wider transversely. The former has a 

 thin external edge ; the latter is separated from the fibular facet by a deep 

 vertical border. I'he crest terminates below at the end of the proximal 

 third of the bone. The shaft at its middle is flattened on the inner and 

 posterior faces, and is rounded on the external side. A bourrelet surrounds 

 the distal extremity just proximad to the astragalar articulation. It is in- 

 terrupted on the inner side by the rather wide groove for the tibialis posti- 

 cus tendon. The anterior and posterior angular extremities of the trochlear 

 crest are of equal length with the internal malleolus. 



The following differences may be observed on comparing the bones of 

 the leg above described with those of Hyrachyus eximius and Anchitheriiim 

 anceps, which they considerably resemble. In the Hyrachyus the great 

 trochanter is less acuminate, and the rotular crests and condyles present 

 greater inequality between the sides. The crest of the tibia is divided in 

 the Hyrachyus, entire in Hyracotherium venticolum. The internal malleolus 

 is lessi produced in the former than in the latter. The resemblance between 

 H. venticolum and the Anchitheriiim is greater. In the latter the principal 

 difference in the femur is the greater anteroposterior extent of the great 

 trochanter. In the tibia the principal difference is the excavation of the 

 spine of the tibia at its summit, in which the Anchitherium resemblest he 

 Hyrachyus rather than the Hyracotherium. 



