392 XOTES O^ THE CANTD^E OF THE WHITE RIYEK. OLIGOCENE. 



bral column, whence it becomes evident that all the limb bones of Cynodictis are propor- 

 tionately shorter than those of Cards, and that the bones of the forearm are especially 

 short. The tibia of Cynodictis differs from that of the modern canines in several par- 

 ticulars. The jjroximal condyles are of nearly equal size, but the external one projects 

 much farther behind the plane of the shaft than in Canis, and on the distal face of the 

 overhanging shelf thus formed is a facet for the head of the fibula, which is much larger 

 and more distinct than in the recent genus. The tibial spine is bifid and very low, but 

 the two parts are closely ajvproxiinated, the condyles being less widely separated than in 

 Canis. The cnemial crest, though stout and prominent, is much less so than in the mod- 

 ern forms, and the sulcus for the extensor longus digitorum is much less deeply incised. 

 In its proximal portion the shaft is stout and trihedral, but for most of its length it is 

 slender and subcylindrical, expanding moderately at the distal end ; it has a double cur- 

 vature, arching forward and outward. The various ridges which serve for the attach- 

 ment of muscles are much the same as in Canis and are, consequently, better developed 

 than those of the femur. The distal articular surfaces of the tibia are intermediate in 

 character between those of Daphmnus and those of Qui is. The grooves for the astraga- 

 lar condyles are deeper and the intercondylar ridge higher than in the former, less so 

 than in the latter, and the sulcus which in Canis invades the articular surface has not 

 yet been developed. The internal malleolus is somewhat smaller than in Daphcenus, 

 but, as in that genus, it forms a heavy, prominent ridge, which extends across the whole 

 dorso-plantar diameter of the bone, while in Canis the process has not half this exten- 

 sion. The groove for the tendon of the long flexor muscle is very distinctly marked and 

 has more elevated borders than in the modern dogs. The distal fibular facet is some- 

 what larger than that of Canis and differs from it in having its principal diameter trans- 

 verse instead of longitudinal. The resemblance in the structure of the distal end of the 

 tibia between Cynodictis and Daphmnus, on the one hand, and the primitive sabre- 

 tooth Dinictis, on the other, is very marked and .very suggestive, though Cynodictis has 

 already begun to change in the direction of the modern Canidm. Among living forms 

 the tibia of Herpestes offers a close analogy to that of the White River genera which 

 have been mentioned. 



The fibula is relatively much less reduced than in the existing Canidm, and both the 

 shaft and the terminations are larger. The proximal end of the fibula is much larger 

 and heavier proportionately than in Canis, and though smaller than in Dinictis, it has 

 a very similar shape; its principal diameter is the antero-posterior one, while trans- 

 versely it is narrow and compressed ; the thickening of the anterior and posterior border 

 is present, as in Dinictis, but much less conspicuous. The facet for the head of the 

 tibia is large, subeireular in shape and proximo-lateral in position. The shaft, though 



