THE .AMERICAN BISOXS. 41 



Their more sheltered and in some other respects somewhat different habitat 

 ■would tend to develop just the differences claimed to distinguish the moun- 

 tain and northern woodland race. 



Castrated buffaloes are said to be occasionally met with where the buffa- 

 loes are abundant, being castrated when quite young by hunters. They are 

 reported to attain an immense size, being so much larger than the others as 

 to be conspicuous from their large size. 



Relationship to the Aurochs. — The American bison is a little smaller 

 than the aurochs [Bison bonasus), with a much larger chest, a smaller and 

 weaker pelvis, a shorter and smaller tail, more shaggy head, and heavier 

 beard. The more important differences, as shown by a comparison of the 

 skeletons, consist in the chest (see subjoined measurements, Table IX) in 

 Bison americanus being absolutely larger than in Bison bonasus, while the 

 pelvis is very small and weak. The B. americanus is hence great]}' devel- 

 oped anteriorly, or in the thoracic portion of the body, with the pelvic 

 portion disproportionately reduced, while in B. bonasus just the reverse of 

 this obtains, — a small compressed thorax and a strong heavy pelvis. This 

 gives the aurochs the appearance of standing higher on its legs. The dor- 

 sal outline is about equally declined posteriorly in each species, not rela- 

 tively much more declined in B. americanus, as generally stated. Neither 

 does the aurochs possess relatively longer hind limbs, as compared with 

 the fore limbs, than B. americanus, the proportion being essentially the same 

 in the two, whether the total height of the animal be assumed as the basis 

 of comparison, or whether the comparison be based on the bones of the 

 limbs alone. 



Comparing, for example, a fine perfect skeleton of a very large old male 

 of each species, beautifully and correctly mounted,* the height of the Ameri- 

 can bison at the highest dorsal spine is found to be sixty-six inches; at the 

 anterior end of the sacrum, fifty-two inches ; which makes the proportion 

 between the two measurements as 80 to 100. The height of the aurochs at 

 the highest dorsal spine is seventy-three inches ; at the anterior end of 

 the sacrum, sixty inches ; making the proportion between the two meas- 

 urements as 82 to 100. This difference is not greater than often occurs 



* These skeletons are Nos. 91 (Bison americanus) and 165 (Bison biinasits) of the. osteological collec- 

 tion of the Museum of Comparative Zoology, both of which were prepared and mounted in the same 

 manner by the same persons, under the supervision of Professor H. A. Ward of Rochester, and represent 

 two pieces of his best osteological work, which is justly celebrated for its neatness and accuracy. 



