Vol. 5] 



Merriam. — John Day Carnivora. 



47 



the neck. Unfortunately the femur of Archaelurus debilis was 

 not known to Cope. 



The tibia is similar to that described for A. debilis, excepting 

 for its larger size, and that there are two grooves for the tendons 

 passing over the posterior side of the internal malleolus on this 

 specimen as in existing felines. This is also the case in another 

 and more nearly perfect tibia (No. 110, pi. 5, fig. 2) showing also 

 the characters of Archaelurus. In the type of A. debilis there is 

 stated to be but one groove. 



The astragalus duplicates the peculiar structure seen in A. 

 debilis, having a very short neck and a rather long inner border 

 of the trochlea. The internal trochlear ridge is separated a little 

 farther from the distal end of the neck than in A. debilis, but a 

 series of otherwise similar specimens of this type shows a slight 

 variation in this character. As has been suggested by Scott, 30 a 

 small facet on the external side of the distal end of the neck cor- 

 responds in position to the cuboid facet of the Ursidae. This 

 facet is, however, continuous with the surface of articulation for 

 the sustentaculum and its articulation probably did not reach 

 beyond the calcaneum. The cuboid articulates closely with a dis- 

 tinct facet near the distal end of the external face of the ectocu- 

 neiform, and is not higher than the ectocuneiform and navicular 

 as it is in the bears. It shows, moreover, no facet for articulation 

 with the astragalus. 



The calcaneum exhibits a strongly marked fossa external to 

 the outer astragalar facet somewhat similar to that seen in Pogo- 

 nodon brachyops, though not so deep as in that form. The sus- 

 tentacular facet is very long, reaching forward to the extreme 

 anterior end of the bone. Separated from the anterior end of 

 this facet by a sharp angle is a small face in articulation with the 

 navicular. In specimen No. 110 the fossa external to the outer 

 astragular facet is deeper and the sustentacula r facet shows a 

 slight median interruption. 



The navicular is considerably produced posteriorly, as was 

 suggested by Cope from his study of the navicular facet of the 

 astragalus. In this specimen the outer side bears a distinctive 



80 W. B. Scott. Osteology of Dinictis f elina., Proc. Philad. Acad., July 

 30, 1889, p. 226. 



