tooth, one well -known in the typical genera of Vkerridce and Mustelidcs. 

 Temnocyon is, however, truly canine in other details, and appears to ap- 

 proach the genus Palceocyon of Lund. According to this author, the 

 posterior inner tubercle of the anterior part of the crown of the sectorial 

 tooth is wanting in that genus, so that it is distinct from the North Ameri- 

 can form. 



Specif. Char. The mandibular ramus is rather deep and compressed, 

 much more so than in the Cards latrans, with which it agrees in the length 

 of the dental series. As compared with the existing species of Ganis and 

 Vulpes of North America, the sectorial tooth is relatively smaller and the 

 premolars larger. In this respect it agrees with most other dogs of the 

 Lower Miocene, and differs from those of the Upper Miocene (Loup Fork).* 

 The posterior tubercle is wanting from the premolars, excepting the last, 

 where it is large and obtuse, differing in this respect also from most recent 

 dogs, and from the cotemporary Cards gregarius. In the sectorial tooth 

 the principal cusp is much elevated above the anterior, while the inner 

 median is small, with its apex in line with the anterior. The cutting edge 

 of the heel is not acute, and is a little external to the median line ; there is 

 a weak cingulum-like angle at its inner base. The first tubercular tooth is 

 large, nearly equaling in antero-posterior diameter the base of the third 

 premolar. It is parallelogrammic in transverse section, and supports two 

 principal cusps and an anterior ledge. The cusps are pronounced and 

 stand exterior to the middle line ; their inner side slopes to the base of 

 the crown where there is no cingulum. The ledge is higher on the inner 

 than the external side. There are no basal cingula on either side of the 

 bases of any of the teeth. The second tubercular molar is lost. 



The alveolar margin of the jaw rises behind the sectorial tooth, and the 

 inferior margin begins to ascend below the middle of the same tooth more 

 decidedly than in C. lupus, latrans or cu^pigerus. The two large mental 

 foramina, are situated, the one below the second, the other below the third 

 premolars. 



Measurements. M. 



Length of anterior six molars 073 



" " four " 045 



" base of second premolar Oil 



Elevation of crown " " Oil 



Length of base of fourth " 015 



Elevation of crown " " 014 



Length of base of sectorial tooth 0185 



Elevation of principal cusp of sectorial tooth 0160 



" anterior " " " 009 



Length of heel of sectorial 007 



Elevation " " 0085 



Length of crown of first tubercular 0115 



* See Proceedings Academy Philadelphia, 1875, p. 22, where I have discussed 

 the origin and history of the sectorial tooth. 



