844 THE JOHN DAY FAUNA. 



and gently convex. The crest sinks rapidly into the head, and the femoral 

 facets are well separated. The tibia resembles that of C. viciacensis, but is 

 more compressed in its proximal half 



Measurements of hind leg. 



M. 



Length of femur .057 



Width of femur at head 019 



Width of femur shaft below third trochanter 009 



Width of femur at epicondyles 015 



Width of condyles of femur 013 



Anteroposterior diameter at condyles .011 



Anteroposterior diameter of head 009 



Diameters of head of tibia ^'*°*''^"P"«'"''"' "l^ 



( transverse 014 



Diameters of distal end of tibia ^'"'t^^^P"^^'""^ '^^^ 



( transverse 0085 



. . .. ■ 1- i ( above middle .. 010 



Anteroposterior diameter < 



<belowmiddle 005 



I have referred to this species in former catalogues of the vertebrate 

 fauna of Oregon as the Castor nebrascensis of Leidy. It is very nearly 

 allied to that species, but I find the following diff'erences: First, the post- 

 orbital constriction is narrower; second, there are fewer fossettes on the 

 posterior half of the molar teeth, but one or two. Leidy figures two or 

 three in the species described by him. 



Castor GRADATus Gope... 



Stenfojiber gradaiiis Cope. Paleontological Bulletin No. 30, p. 1, December 3, 1878. Proceedings Ameri- 

 can Philosophical Society, lrt78 (1879), p. 63. 



Plate LXIII; tig. 2-2. 



This species is represented in my collection by parts of several indi- 

 viduals. One of these is a palate with both series of molars ; a second is a 

 mandibular ramus with all the molars. The best specimen is a cranium, 

 which is nearly perfect, the principal deficiency being the absence of the 

 mandibular rami. It is of smaller size than the S. nebrascensis and S.jyatisus, 

 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, wliose grinding face does not present more than one-third 

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

 third liave their long axes transverse. In all the crowns, besides the 

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



