1 899- J Wort man and Matthew, Ancestry of the Canidce, etc. I 1 9 



known representative comes from the Wind River beds, and is 

 known from only an imperfect fragment of a lower jaw in the 

 Museum collection. In the Bridger the genus is represented by 

 at least two species, one of which, V. palustris, was described by 

 Marsh from a single superior molar and forms the basis of the 

 genus ; and the other, V. parviiforiis, was described from a frag- 

 ment of a lower jaw by Cope and made the type of his genus 

 Miacis. In the Museum collection is a specimen which upon 

 careful comparison with Marsh's type of V. palustris we identify 

 with this species ; it consists of two superior molars of the right 

 side, two nearly complete mandibular rami, together with some 

 fragments of the skeleton of the limbs (No. 2305). It was found 

 by Mr. O. A. Peterson of the Museum party of 1895, and was 

 obtained from the middle horizon near the extreme southern 

 limits of the Washakie Basin. 



Fig. 4. Vulpavus palustris Marsh, 

 size. No. 2305. 



Lower jaw, natural 



Fig. 5. V II Ipav lis pa- 

 lustris Marsh. Upper 

 teeth, twice natural 

 size. No. 2305. 



The superior molars are two in number and display about the 

 same proportions as those of many of the existing Canidae. They 

 present a number of features, however, very different from the 

 modern Dogs. The first molar is remarkable for the great elonga- 

 tion of its anterior side in comparison with the posterior, and the 

 drawing out of the antero-external angle, as well as the unusually 

 broad ledge intervening between the base of the external cusps 

 and the outer border of the crown. Another marked feature of 

 this tooth is the great disparity in size between the anterior exter- 

 nal and the posterior external cusps. The antero-internal cusp is 

 large and lunate and there is a distinct anterior and posterior in- 

 termediate. The postero-internal cusp is represented by a strong 

 cingulum in the usual position but it does not rise up into a dis- 

 tinct cusp as in the later Canid?e. The second molar is similar 



