HATCHER : OLIGOCENE CANTD^ 103 



The structure of the talon lias been somewhat obliterated by wear, but it appears to 

 have been composed of a large median cone or ridge homologous with the external 

 cone of the heel in Daphoenus and a rudimentary internal cone. 



M. 2^ is much reduced in size and its structure has been obliterated by wear to 

 such an extent that it is impossible to determine its exact character. 



M. 3 is wanting on both sides, but the single rather small alveolus indicates that 

 it was much reduced in size. 



The VERTEBR.E. PI. XVIII., Figs. 6, 7, 8. 



Of the vertebrse only the atlas, axis, and the third cervical are preserved. 

 These, as in Daphoenus, are feline rather than canine in character. The transverse 

 processes of the atlas are wanting. The articular surfaces for the occipital condyles 

 are deeply concave and rather widely expanded, while those for the axis are nearly 

 flat and but little expanded, diverging from the longitudinal axis at an angle of 

 scarcely more than fifteen degrees. The vertebrarterial canal is somewhat interme- 

 diate in character between that of the dogs and cats. It enters on the inferior side 

 at the middle of the base of the transverse process and emerges posteriorly at the 

 supero-posterior border of the base of the same process, instead of directly in the 

 middle, as in Daphoenus and modern cats. The position of the posterior opening of 

 the vertebrarterial canal in the present genus and species while still similar to that 

 which obtains in Daphoenus and the cats is clearly shifting to that which it occupies 

 in the dogs. In this respect Protenmocyon may be considered as having made a dis- 

 tinct advance over Daphoenus in the direction of recent dogs. 



The axis is in a splendid state of preservation. The spine is high and sharp, 

 and posteriorly it is continued into a long peg-like process as in the cats instead of 

 being truncated as in the dogs. The odontoid process is peg-like. There are rather 

 slender transverse processes directed backward and slightly downward. Inferiorly 

 there is on the centrum a sharp median keel. Cervical three does not differ ma- 

 terially from the same vertebra in recent cats. 



Principal Measurements of Type (552). 



Greatest length of skull 167 mm. 



" breadth " 85 



Length of sagittal crest 68 " 



Breadth of cranium at greatest temporal constriction 23.5 " 



Greatest breadth of cranium 46 " 



" frontals 36 " 



Length of palate 81 " 



distance from incisive alveolar border to anterior border of orbit 65 ' 



