On some of the Characters of the Miocene Fauna of Oregon. 



(Bead before the American Philosophical Society, November 15, 1878.) 



By E. D. Cope. 



We have been for some time in possession of information as to the ungu 

 late forms which inhabited Oregon during the Miocene period. Through 

 the labors of Profs. Leidy, Marsh and Bettany, we have learned of the 

 existence there of Oreodontidce in considerable variety ; of Anchitheriidce ; 

 of peccary-like species ; of Elotherium, and of Rhinocerits. But of the un- 

 guiculate types, of Rodentia, and of the inferior orders of Mammalia, 

 almost nothing is yet known. Having recently received a number of 

 specimens from the deposits in question, I am in a position to offer a 

 number of new identifications. The following species already known 

 from the Miocene of Colorado, I find contained in the collection, viz. : 

 Palmolagus haydeni ; Canis gregarius ; Canis lippincottianm ; Hyper - 

 ragulus calcaratus ; Leptomeryx evansi. 



Rodentia. 

 Steneofiber gradattjs, sp. nov. 



This species is represented in my collection by a cranium which is nearly 

 perfect, the principal deficiency being the absence of the mandibular rami. 

 It is of smaller size than the 8. nebrascensis and 8. pansus, and differs from 

 both these species in the relative sizes of the superior molar teeth. The 

 first of these is the largest, and the others diminish regularly in size to the 

 last, whose grinding face does not present more than one-third the ex- 

 tent of that of the first. The triturating surfaces of the second and 

 third have their long axes transverse. In all the crowns, besides the in- 

 ternal and external enamel inflections, there is but one fossette, which is 

 anterior to the external inflection. The latter has become isolated from 

 the superficial enamel on the last three molars, by attrition. The superior 

 incisors are flat anteriorly with the external angle rounded, and its dentine 

 presents the transverse undulations seen in 8. pansxos. 



Measurements. M. 



Length of skull from incisive alveolus 0500 



"Width between summits of first molars 0060 



fourth " 0095 



Length of molar series 0115 



-p.. . c ., „ r. . 1 (antero-posterior 0040 



Diameter of the first molar < 1 - 



{. transverse 0045 



Diameter of third molar I antero-posterior 0028 



t transverse 0032 



tv , . c e ,, -, f antero-posterior 0020 



Diameter of fourth molar \ l n t 



I transverse 0024 



From the above measurements it is apparent that the molar series in this 

 species is equal in length to the anterior three molars cf the 5. nebrascensis 



