316 F. B. Loomis — Osteology and Affinities 



The patella is broadly oval and simple in outline, having 

 nothing of the prolonged process common to later Tylopoda. 

 The slender tibia is about a fourth longer than the humerus, 

 which, when compared with other tylopoda, is not long. The 

 facets for the femoral condyles are wide and 

 Fig. 22. nearly flat, being separated by a bifid tubercle. 



The cnemidial crest is extremely prominent, and 

 extends about a third of the way down the bone. 

 In the regions of the crest the cross section is 

 triangular, but below the section is transversely 

 oval. The distal end of the bone is expanded 

 Fig. 22 Patella. anc [ ^ ne i nner astragular facet much wider and 

 ' ' shallower than the outer, the two being sepa- 



rated by a prominent septum. Both these facets and that on 

 the septum are interrupted in the middle by a shallow depres- 

 sion, which extends from near the inner margin of the inner 

 facet all but to the outer margin of the outer facet. This is a 

 very marked characteristic of the modern camels, and begins 

 as far back as in Poebrotherium at least. The fibular facet is 

 divided by the groove for the fibula shaft into anterior and 

 posterior portions. 



The proximal end of the fibula is reduced to a tiny spine 

 fused to the fibula; the distal end to a nodular bone wedged 



Fig. 23. 



Fig. 23. Stenomylus hitchcocki, tibia and fibula from the anterior 

 side, x 1/2. 



in between the tibia and th.e calcaneum. It presents a tiny 

 spur above, vestige of the original shaft, which fits into the 

 groove on the tibia; and has a long continuous facet for 

 articulation on the tibia. On the inner surface is a crescentic 

 grooved facet for the astragulus, and on the lower surface a 

 concave face for the calcaneum. 



In conformity to the slender build the tarsus is narrow and 

 high. The astragulus is narrow, with the external condyle 

 somewhat higher than the internal. On the distal trochlea 

 the facet for the cuboid is relatively narrow, while that for the 

 navicular is proportionally wide. The plantar facet is com- 

 paratively narrow and small. In general, however, the 

 astragulus would be recognized as tylopod. The calcaneum is 

 of moderate length, being distinguished only by the consider- 



