346 Wortman — Studies of Eocene Mammalia in the 



an internal position the beveled portion is large as in the present 

 species, and when they have an external position the beveled 

 portion is reduced and its position is taken by the basin- 

 shaped part. Taking the present species as one extreme and 

 the modern dogs as the other, the genus Cynodictis stands 

 about midway between the two in this respect. 



The second molar is a diminished copy of the sectorial with 

 the exception that the trigon is much less in height, and there are 

 less distinctive shears developed among the elements of the 

 trigon. The cusps as well as the heel have approximately the 

 same relations to each other. In Cynodictis and the modern 

 dogs this tooth, as well as the succeeding one, has lost all 

 traces of the sectorial structure. The third molar is still more 

 reduced, being relatively as small as in. the modern species; 

 the crown, however, still retains traces of the tuberculo-sectorial 

 pattern, although but faintly. 



Figure 3. — Left upper jaw of Vulpavus Hargeri Wortman ; crown view ; one and 

 one-half natural size. (Type.) 



Of the superior dentition, figure 3, the canines are of moderate 

 size and pointed, resembling those of the Miocene Cynodictis. 

 The first premolar is a small single-rooted tooth placed 

 close to the base of the canine ; a short diastema intervenes 

 between it and the second. The second and third are, as is usual 

 among the Canidse, two rooted, with laterally flattened, pointed 

 crowns; the third has a posterior basal and accessory cusp 

 like the corresponding tooth in Cynodictis. The superior secto- 

 rial displays the usual form seen in the Canidse, although in 

 some respects it is primitive. The two external cusps are 

 large and modified into very efficient shearing blades. At the 

 base of the large antero-external cusp is seen a small tubercle 

 which recalls the structure of the superior sectorial among the 

 carnivorous viverrines. In this latter group, however, it is 

 larger and more distinct, while among the cats and hyaenas it 

 has been developed into a powerful third blade. The genus 

 ^Elurodon^ a dog-like mammal from the Loup Fork Miocene 

 of America, likewise exhibits this cusp but in a less degree of 

 development. The internal cusp is unusually large and has an 

 anterior position, displaying about the same proportions as are 



