Marsh Collection, Peabody Museum. 



427 



remarkable for the great anteroposterior diameter of the con- 

 dyles, exceeding the dog in this respect, and quite equaling 

 some of the Artiodactyle Ungulates. There 

 is a distinct popliteal fossa, the inner edge 

 of which is prominent and marked at its 

 lower extremity by an oval facet, for a 

 rather large popliteal fabella. The prom- 

 inence of this part of the bone indicates 

 unusual strength for the tendinous origin 

 for the outer and inner heads of the gas- 

 trocnemius, which is well in accord with 

 the cursorial powers of the species. The 

 condyles are subequal in size and the inner 

 projects to a slightly lower level than the 

 outer. There is a deep intercondylar notch 

 leading forward into a well-marked rotu- 

 lar groove. 



The patella is relatively larger than that 

 of the dog ; it is elongated, narrow from 

 side to side, and rather thick from before 

 backwards. The proximal extremity is 

 truncated and roughened for the attach- 

 ment of the large quadriceps tendon. It 

 has the typical form of a running animal. 



The Tibia and Fibula. (Figures 59, 

 60.) — The tibia, as in the dog, is a trine 

 shorter than the femur. The head dis- 

 plays two subequal depressions, of which 

 the outer is slightly the larger, to receive 

 the femoral condyles. The spine is bifid, 

 but the separation is not so clearly evident 

 as it is in the dog. The cnemial crest is 

 very large and extends more than half-way 

 down the shaft, whereas in the dog it is 

 limited to the upper third. The upper 

 posterior portion of the shaft is deeply 

 excavated. The inferior extremity exhibits 

 a trochlear surface similar to that of the 

 dog. The internal malleolus is a strong 

 process and the trochlear grooves are pronounced. 



The fibula has a relatively stouter shaft than that of the 

 dog, but at the same time is much reduced ; it is applied to the 

 lower end of the tibia for a considerable distance. The shaft 

 is triangular above and oval in cross-section below. The dis- 

 tal end is large, and forms a stout external malleolus in the 

 ankle joint ; it articulates with the astragalus by means of a 

 lateral facet, and does not touch the calcaneum. 



Figure 59. — Tibia 

 and fibula of Dromocyon 

 vorax Marsh ; anterior 

 view; one-half natural 

 size. (Type.) 



