

Marsh Collection, Peabody Museum. 443 



are three true molars in either the upper or lower jaw. 

 Although the typical genus Viverra is known with reason- 

 able certainty from the Upper Eocene deposits of Europe, the 

 molar formula is remarkably persistent, being two above and 

 below. The femur again shows in its incipient backward 

 curvature, as well as in the lateral position of the lesser 

 trochanter, that Vulpavus is more nearly allied to the dogs 

 than to the civets. 



But this evidence from the incomplete skeletal remains, 

 while it is very strongly presumptive of canine relationship, is 

 not at the same time absolutely conclusive. It, however, 

 receives powerful additional support from a consideration of 

 the forms intervening between it and Cynodictis of the 

 Oligocene, of the canine affinities, of which there cannot be 

 the slightest question. From the Washakie Beds, which appear 

 to be somewhat later than the Bridger, comes the genus 

 JVeovulpavus, in which the superior molars had been reduced 

 to two, giving the molar formula of the modern genus Canis. 

 In the succeeding Uinta or Uppermost Eocene stage the genus 

 Procynodictis furnishes a nearer approach in the structure of 

 the molars, in that the two external cusps are subequal in size, 

 are more widely separated and the antero-external angle is less 

 prominent. In the carpus, the scaphoid, lunar, and centrale 

 were fused into a scapholunar and the feet were much like 

 those of Cynodictis. It will thus be seen that the evidence as 

 far as it is obtainable points very strongly to a genetic rela- 

 tionship between Vulpavus and Cynodictis, and from this 

 latter without doubt sprang a large number of the modern 

 species of the Canidse. 



Progressive Modification of the Canidce. 



Regarding this, then, as the oldest and most primitive link in 

 the true canine phylum that has yet been discovered, it is a 

 matter of more than passing interest to examine into the bear- 

 ing of its osteological structure upon the origin and evolution 

 of the central group of the living dogs. The characters in 

 which this group has shown evolution may be summarized as 

 follows: The brain has increased greatly in size, both rela- 

 tively and actually, having been especially widened in front ; 

 the superior molars have been modified in structure, in that 

 they have largely lost that characteristic anterior transverse 

 elongation so common to the Eocene types, but have, on the 

 other hand, developed a large postero-internal cusp from the 

 cingulum and a strong tendency to the formation of a second 

 posterior internal cusp ; the number of the superior molars 

 has been reduced to two, the sectorial of the superior series 



