no. 2086. SOME MAMMALS OF THE PLEISTOCENE— HAY. 



£170 



Showing diameters of bones in hundredths of the length. 



Bones compared. 



E.laurentius? . 



No. 7857. 



100 



100.0 



36.3 



31.9 



13.3 



12.4 



29.4 



27.6 



100.0 



100.0 



27.2 



26.5 



9.8 



8.8 



14.1 



13.1 



23.8 



22.5 



20.0 



19.8 



100.0 



100.0 



23.4 



23.4 



12.6 



13.1 



15.9 



16.0 



22.0 



23.4 



100.0 



100.0 



71.0 



78.4 



47.3 



43.0 



56.6 



59.5 



100.0 



100.0 



133.0 



152.8 



124.0 



127.7 



130.3 



141.7 



No. 7923. 



Humerus, length 



Greatest width at upper end 



Side-to-side diameter at middle 



Diameter across lower end 



Radius, length 



Greatest width at upper end 



Fore-and-aft diameter at middle 



Side-to-side diameter at middle of length. 



Greatest width near lower end 



Width of distal articular surface . . 



Median metacarpal, length 



Side-to-side diameter of upper end 



Fore-and-aft diameter at middle of length 



Side-to-side diameter at middle of length . 



Side-to-side diameter at lower end 



First phalange, length . 



Width of upper end 



Width of middle of length 



Width at lower articular surface 



Second phalange, length 



Width of upper end 



Width of middle of length 



Width across lower articular surface 



100.0 



34.2 



13.7 



28.4 



100.0 



28.0 



10.1 



13.8 



24.8 



21.8 



100.0 



22.8 



13.2 



16.6 



22.0 



100.0 



70.1 



46.0 



59.7 



100.0 



144.0 



122.0 



129.2 



A study of the tables just presented shows that there is, among 

 the bones of the four limbs measured, a considerable amount of dif- 

 ferences, not only in length but in proportions. The humerus of 

 E. laurentiusf is shorter than either of the other two fossil forms; 

 it is also thicker at the ends, while the diameter at the middle of the 

 bone is, relatively to the length, greater than in No. 7857, less than 

 in No. 7923. On comparing the humeri of the numbers just men- 

 tioned it is seen that the first mentioned is slenderer than the others. 



The radius also of E. laurentiusf is shorter than it is in the other 

 two limbs, whose radii are of about equal length. That of E. lauren- 

 tiusf is intermediate in its diameter between the other two in the first, 

 second, and fourth measurements. As regards No. 7857 and 7923, 

 the radius of the latter is in all respects a stouter bone. 



The median metacarpals of the three fossil limbs are much alike 

 in their proportions and there are relatively small differences in their 

 absolute lengths. That of E. laurentius is slightly slenderer than 

 those of the other two. As compared with the Arabian horse, the 

 three fossil forms have the metacarpals considerably stouter. 



The first phalange of E. laurentiusf is shorter than that of each 

 of the other two limbs. That of No. 7857 is relatively broader at 

 the ends and more constricted at the middle. In all three the bone 

 is heavier than it is in the Arabian horse. 



Greater differences in proportions are found among the second 

 phalanges; it is possible that these short bones, broader than long, 

 afford greater individual variations than the longer bones. 



To the writer it appears that the measurements of the limb bones 

 above recorded indicate with considerable certainty that there ex- 

 isted in the region of northwestern Nebraska, in the early part of 



