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 



Bx'eadth 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: 



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



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



Thickness, before backward, at the same position, 



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



Width from before backward and obliquely between the two median 

 pyramidal processes, ...... 



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



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



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 



Inch. 



Lin 



5 



4 



1 



10 



1 



4 



3 



3 



2 



6 



2 



1 



1 



7 



