m'clung: skeleton op bison OCCIDENTALIS. 251 



Inches. Inches. 



Extreme width of barrel at tenth rib 22 V^ 25% 



Length of humerus 15 151^ 



Length of femur 16 % 20 % 



Least circumference of humerus 6 7% 



Least circumference of femur 6l^ 6% 



Diameter of humeroradial joint ZV2 4V4 



Diameter of femurotibial joint 4% 51^ 



Width of 5th cervical vertebra across transverse pro- 

 cesses 51/2 5% 



Length of fore leg, exclusive of humerus 26 29% 



Length of hind leg, exclusive of femur 32 36 



t)iameter of tibiotarsal joint 2% 3% 



Diameter of humerocarpal joint SVi 4% 



Length of longest dorsaf spine 18 25 



Diameter of humeroradial joint in per cent, of humerus 



length 23.3 27.4 



Diameter of femurotibial joint in per cent, of femur 



length 26.1 26.8 



An examination of these figures will show that the extinct 

 species was considerably larger than the living one, and that 

 it differed materially in some respects from the one with which 

 we are familiar. In the extremes of length and height there 

 are differences of sixteen inches. On the contrary, in the pel- 

 vic region there is a variation of only seven inches in height. 

 The unusual development of the neural spines in the dorsal 

 region of course accounts for this excessive height. That 

 there is not, for this reason, a greater slope to the back is ex- 

 plained by the measurements of the two pairs of legs. In Bison 

 bison the height of the fore leg is ten inches less than that of 

 the hind leg; in B. occidentalis the fore leg is fourteen inches 

 shorter than the hind leg. This strong growth of the posterior 

 members gives the larger bison a racy appearance, and despite 

 the great depth of the body, fifty inches, there is the sugges- 

 tion of speed and lightness. Possibly this may be due also to 

 the fact that while there is a difference of fourteen inches in 

 the depth of the bodies of the two species, there is a variation 

 of only three inches in width. There is very little difference in 

 the length of the fore leg in the two specimens, but the diam- 

 eter is materially greater in B. occidentalis — a character corre- 

 lated with the greater weight to be borne. This strengthening 

 of the fore leg is indicated in another way. The diameter of 



