1867.] 



317 



Agassiz.] 



of the skulls of the American bison and the Euroi?ean au- 

 rochs. 



He said that it was necessary to. reexamine the pi'oofs of their spe- 

 cific distinction adduced by American writers, because Brandt had 

 recently denied their accui-acy. Professor Agassiz stated that, if the 

 way in which sjiecies had been separated during the last half century, 

 in accordance with the principles carried out by Cuvier in his Re- 

 cherches sur les Ossemens Fossiles, was to be considered as a stand- 

 ard of scientific accuracy, then the bison and the aurochs were 

 certainly two species. By some writers, these animals had been 

 considered generically distinct from our domestic cattle, under the 

 name of Bison, while the name Taurm was applied to the common 

 oxen. The musk ox is designated by the name of Ovlhos, that of 

 Buhalus retained for the buffaloes of India and Africa. In the group 

 to which the European and American bison are referred, the skull 

 projects backward beyond the horns, and the tojJ of the head between 

 them is rounded. In the group including our cattle, there is no such 

 jirojection of the skull, and the back and top of the head meet to 

 form a sharp, straight ridge, between the horns; the united parietal 

 bones are also developed into a triangular wedge-like piece, unlike 

 that of Taurus. Professor Agassiz said he was inclined to believe 

 that these distinctions had a generic value. He then proceeded to 

 point out the following distinctions between the skulls of the Ameri- 

 can and Eurojjean Bisons, specimens of which were exhibited. 



AMERICAN BISON. 



EUROPEAN AUROCHS. 



Muzzle formed by the in- 

 termaxillary bones. 



Triangular projection of 

 united parietals. 



Form of lachrymals. 



Upper portion of forehead. 

 Root of nose. 

 Choanoe. 



Temporal depression. 



Space occupied by three 

 foremost grinders. 



Toothless portion of jaw. 



Broad and square. 



Regular, tapering 

 point. 



Advance over the upper 

 maxillaries, reaching 

 nearly to the opposite 

 edge ; bone very ob- 

 tuse. 



Not prominent. 



Flat. 



Oval, running to palate. 

 Broader than in the European species. 



Square, and cut trans- 

 versely. 



Extended, tapering to a 

 rounded edge. 



Tapering gradually, not to 

 a point, and ending in a 

 transverse suture. 



Advance only half way 

 toward the opposite 

 edge of upper maxilla- 

 aries ; bone almost 

 square. 



Rising and prominent. 



Prominent. 



Smaller in Bison than in Aurochs. 



Larger in Bison than in Aurochs, particularly in 

 lower jaw, the end of which is dilated. 



