Marsh Collection, Peabody Museum. 145 



apparently of several others. The lower jaws in this genus 

 are long, slender and compressed ; the last two lower molars 

 are tubercular. Both have the posterior part of the crown 

 quite low and the anterior half elevated and composed of three 

 angular cusps. The four teeth anterior to these are much 

 compressed. The upper flesh tooth closely resembles that in 

 some of the Viverridse and the genus should probably be 

 referred to that group." * The species thus far referable to 

 this genus are numerous, of which one, V. haydenianus, from 

 the Torrejon ; four, V. leptomylus, jorotenus, massetericus, 

 and curtidens, from the Wasatch ; and two, V. gracilis 

 (dawkinsianus) and altidens, from the Wind River beds, have 

 been described by Cope. It will thus be seen that the genus 

 has a very great vertical range, greater, in fact, than any 

 known contemporary group of mammals throughout the whole 

 Eocene. With the close of the Bridger epoch, according to 

 our present knowledge, the genus disappeared from this 

 country, since no remains of it have as yet been found either 

 in the Uinta, White River, or John Day deposits. f It is pos- 

 sible, however, that the group may have continued to exist 

 to a much later date on this continent, and that they retreated 

 to the southward along with the tropical fauna which disap- 

 peared from Wyoming at the close of the Eocene. It is pos- 

 sible, therefore, that their remains will yet be found in the 

 Miocene of the South, but this, of course, is merely conjectural. 



Viverravus gracilis Marsh. 

 Didymictis dawkinsianus Cope, Tertiary Vertebrata, 1884, p. 310. 



The type, figures 18, 19, consists, as Professor Marsh has 

 stated, of parts of both mandibular rami and a superior secto- 

 rial, but there are at least twenty individuals of the species 

 represented in the collection by various fragments. Of the 

 type the right ramus is the more perfect of the two, and carries 

 the third and fourth premolars and the first and second molars. 

 The alveoli for the first and second premolars, together with 

 that for the root of the canine, are represented. All the pre- 

 molars are two-rooted, even the first, which among the Carni- 

 vora is very generally a single-rooted tooth. The third and 

 fourth premolars have high pointed crowns, with anterior and 

 posterior basal cusps, together with a distinct and trenchant 

 accessory cusp. The sectorial has the trigon much elevated 



* Loc. cit , p. 7, of separata. 



f A possible exception to this statement may be found in the imperfectly known 

 genus Buncelurus of Cope, from the White River Oligocene of Colorado. When 

 more fully known, it will not be at all surprising fco find that this genus is a direct 

 descendant of Viverravus. 



