1902.] DOUGLASS — CRETACEOUS AND LOWER TERTIARY. 223 



Torrejon. They more resemble in some respects the corresponding 

 bones of Coryphodon. 



The ulna is much larger than the radius, is broad antero-poste- 

 riorly but narrow transversely. The upper portion of the olecranon 

 is broken off, but a cross section above the glenoid cavity is trian- 

 gular with the anterior edge thin. The sigmoid cavity is convex 

 transversely. The outer portion is much less convex longitudinally 

 than the inner ; it extends lower and its upper portion makes an 

 oblique emargination on the outer side of the olecranon. There are 

 two fairly large surfaces for articulation with the radius. The upper 

 outer surface of the bone has a quite deep longitudinal furrow which 

 dies out near the middle of the shaft. The inner surface is longi- 

 tudinally concave from the olecranon to the enlargement near the 

 distal end of the bone, where there is considerable swelling and 

 roughening. The distal articular surface is elliptical, slightly con- 

 cave palmo-dorsally and convex transversely. This surface is very 

 slightly oblique to the long axis of the bone. 



The radius is subcylindrical above. The head is partly broken, 

 but the surface for articulation with the humerus is shallow and 

 appears to have been nearly circular. There is a longitudinal 

 roughening on the ulnar side, to correspond with similar rugosities 

 on the radial side of the ulna. Below these is a rugosity on the 

 antero-inner side of the radius and on the opposite side. The bone 

 has the appearance of being twisted on itself. The form of the 

 bone suggests freedom of motion of the limb other than a fore-and- 

 aft movement. 



A proximal and medial phalanx apparently do not differ greatly 

 from those figured in Osborn's paper on '* Evolution of the Ambly- 

 poda."^ 



M. 



Length of ulna from upper portion of glenoid cavity .1970 



Antero-posterior diameter at middle of shaft . .0310 



Transverse diameter at middle of shaft . . .0143 



Transverse diameter of shaft of ulna at middle . .0195 



Pantolambda cavirictis Cope (?). 



Fragments of upper jaw, with teeth from which enamel has been 

 removed. The size is nearly the same as the corresponding teeth 



i Bull. Anier. Mus. Nat. Hist., Vol. X, p. 187. 

 PROC. AMER. PHILOS. 80C. XLI. 170. O. PRINTED SEPT. 23, 1902. 



