652 THE WASATCH AND BEIDGEE FAUN^. 



Depth of ramus at Pm. iv, .011; length of Pm. iv, .0065; external Vs obtuse. 



P. sylvaticus. 

 Depth of ramus at Pm. iv, .017; length of Pm. iv, .0065; external Vs acute angled. 



P. cinctus. 



P. sylvaticus and P. vulpiceps present an intermediate tubercle in the 

 second inferior true molar, a character not present in P. vintamis and cristo- 

 nensis. The peculiar appearances seen in Prof. Owens's figure of the last 

 inferior molar of P. vulpiceps are due, according to its describer, to injuries 

 produced in extracting it from the matrix. 



This genus occupies an intermediate position between Hyracotherium 

 and Lophiotherium. 



Pliolophus cinctus Cope. 



Cligotomus cinctus Cope. Paleontological Bulletin No. 12., p. 2, March 8, 1873. Annual Report U. S. 

 Geol. SuTV. Terrs., 1872 (1873), p. 607. 



Plate XXIV, fig. 26. 



The only indication of the former existence of this species which I pos- 

 sess, is a mandibular ramus which supports the fourth premolar and the first 

 true molar, and contains the alveoli of the other premolars, and the second true 

 molars. There is a^ pretty long diastema behind the first premolar, and the 

 second premolar was almost as large as the third. The fourth scarcely dif- 

 fers in any respect from the first true molar, a circumstance which led me, 

 when I first described the species, to regard it as a true molar. Both this 

 tooth and the first true molar are characterized by the acuteness of the 

 external cusps and the distinctness of the oblique ridges which extend in- 

 wards from them, both anteriorly and posteriorly. The sections of these 

 lobes form Vs, but they are distinct from the internal cusps, so that they 

 are not identical with the molars of the species of the Chalicoiheriidoe. The 

 anterior inner cusp is slightly bifid. The external base is surrounded by 

 a distinct cingulum, which passes round behind the crown and supports a 

 median tubercle. 



The ramus is rather shallow and has flat sides. The mental foramen 

 is below the posterior limit of the diastema. 



