No. 2.] THE RELATIONS OF PROTOCERAS. 349 



the spine is bifid and unusually high, but this may in part 

 be due to the crushing which the specimens have under- 

 gone. The cnemial crest is very prominent, ends above in a 

 massive rugosity and the sulcus for the peroneal .tendon is 

 deeply incised. The shaft has the characteristic double cur- 

 vature, both anteriorly and laterally, and the general shape 

 found in the smaller Pecora. According to Osborn and Wort- 

 man, the astragalar surface is constituted very much as in the 

 deer {Cariacus). 



The proximal portion of the Fibula is coossified with the 

 tibia, as in MoscJms, Tragulus, etc., and as this portion is con- 

 siderably thicker proportionately than in the genera named, it 

 is likely that a good length of the slender, filiform shaft was 

 preserved in the living animal. Osborn and Wortman state 

 that the distal end forms a distinct malleolar bone, which is 

 shaped as in the Pecora and wedged in between the calcaneum 

 and the distal end of the tibia. They find reason to believe, 

 however, that in the fully adult animal the two bones may coa- 

 lesce, as in the tragulines. In the latter group the malleolar 

 bone, even when separate from the tibia, as according to Flower 

 it sometimes is in Dorcatheriiim, has quite a different shape 

 from that of the Pecora. The tibia and fibula of Leptomeryx 

 are remarkably like those of Protoceras in almost every respect. 



The hind foot has already been described by Osborn and 

 Wortman, but it will be necessary to go over the same ground 

 with somewhat more fullness, in order to display the range of 

 variability in this structure, and to bring together all the ma- 

 terial for comparison in attempting to estimate the systematic 

 position of this extraordinary genus. 



The Tarstis (PL XXII, Fig. 18) unites a condition of primi- 

 tiveness with highly advanced characters. The calcaneum is 

 thoroughly pecoran in shape ; the tuber is quite elongate (more 

 so than in Moschus, less than in Cerviis or Gelocus), compressed, 

 with nearly parallel dorsal and plantar borders, tapering less to 

 the distal end than in the musk-deer, and with less definitely 

 marked tendinal sulcus on the free end. The sustentaculum 

 is very prominent and at once distinguishes this calcaneum 

 from that of any of the oreodonts. The fibular facet is not so 



