270 ON THE EXTINCT MAMMALIA OF 



and about fifteen lines in height. The longest diameter of the posterior part of the 

 condyles is twenty-two lines, which is also the length of the inferior part. The latter 

 extends upon the basilar process an inch in advance of the anterior edge of the occipi- 

 tal foramen. 



11. The lower extremity of a humerus, from the Niobrara River. The specimen 

 comparatively of moderate proportions. Its measurements are as follow : 



Inch. Lin. 



Circumference of the shaft four inches above the inferior lateral edge of 



the articular surface, . . . . . .48 



Breadth of the articular surface, . . . . .26 



Width, from before backward, of the internal condyle, . . .3 



Width of the external condyle, . . . . . . 1 10 



12. The lower extremity of a radius, agreeing in size and proportions with the 

 same portion of the bone in the ordinary Domestic Horse. From Pawnee Loup River. 

 Its measurements are as follow : 



Inch. Lin. 



Circumference of the shaft three inches above the inferior lateral edge of 



the articular surface, . . . . . .55 



Breadth of shaft at same position, . . . . .2 



Thickness, before backward, at same position, . . . ,12 



Breadth at lateral tuberosities for ligaments of the carpal articulation, . 3 

 Breadth of carpal articular surface, . . . . ,26 



13. The lower extremity of a tibia, about the size of the corresponding portion of 

 the same bone in the common Horse. From the Niobrara River. Its measurements 

 are as follow: 



Inch. Lin. 



Circumference of shaft five inches above apex of the pyramidal process, 5 4 



Breadth, from side to side, at the same position, . . . 1 10 



Thickness, before backward, at the same position, . . .14 



Breadth at the lateral tuberosities of the ankle, . . . .33 



Width from before backward and obliquely between the two median 



pyramidal processes, . . . . . .26 



Width of the articular end internally, . .• . . .21 



Width of the articular end externally, . . . . .17 



14. A patella, of the same size as in the ordinary Horse, from the Niobrara River. It 

 measures three inches in breadth and depth, and the articular surface is thirty-four 

 lines in breadth and twenty-seven lines in depth. 



15. Seven astragali from the sands of the Niobrara River, of the same form but 



