504 THE EOCENE PERIOD. 



many Creodonts. The long axis of the astragalar face is slightly oblique to 

 the transverse long axis of the head, tending backwards towards the inner 

 side. In this respect it is identical whith Phenacodus vortmani. In Hyra- 

 cotheriuni venticolmn the two axes are parallel. The tibia is much smaller 

 than that of Phenacodus vortmani, and with the femur, prove that the pos- 

 terior limb is little if at all longer than the anterior limb, as is the case in 

 that species. The patella is an elongate oval, less robust than that of Phena- 

 codus vortmani. It is rounded above and narrowed below. 



Measurements of hind leg. 



M. 



Diameter of head of femur No. 1 0115 



Length femur No. 2 from base of little trochanter, distad v , 059 



Leugth femur No. 2 from inferior base of third trochanter, distad 049 



Width of condj'les posteriorly 023 



Elevation of rotular groove at external condyle 024 



Width of rotular groove with crests 0095 



Length of patella 016 



Proximal diameter patella ^^°*''^°P°«*«"°'' ^'>'' 



( transverse 0085 



Length of tibia 097 



Diameters of head ^='"t«''°P°«t''"'"- «20 



c transverse 023 



Diameters of shaft at middle ^'^"**^°P°^*^''''"' • 0°^ 



( tr.ausverse 0065 



Diameters distal end ^'*"t''™P"-^*''"°' 0^95 



< transverse 012 



The ealcaneum is remarkably elongate, and is but little expanded an- 

 teriorly. The free portion is compressed. The astragalar condyle has a 

 peculiar position. It is placed diagonally across the middle superior ridge 

 of the free portion, and presents its articular surface chiefly forwards. The 

 sustentaculum is deep, short, and narrowed to a knob. The cuboid facet is 

 concave vertically, and very oblique transversely, retreating on the inner 

 side. Its form is subquadrate, with the sides oblique, and the superior and 

 exterior angles produced and rounded. The latter marks the extremity of 

 the external distal ridge, which extends from the calcaneal condyle. 



Numerous astragali are preserved, but none accompany the specimen 

 which has furnished most of the skeleton above described. This bone in 

 this species looks much like that of a species of Stypolophus. The inner 



