EXTINCT BISONS OF NORTH AMERICA— HAY. 



179 



BISON CRASSICORNIS Richardson. 



In his paper on The Fossil Bisons of North America, Lucas pre- 

 sented iUustrations of three partial skulls of this species, all of which 

 had been brought from Alaska. Since the publication of that paper 

 a number of other specimens have come to light; and it is proposed 

 to illustrate here some of these. Unfortunately up to this time, so 

 far as the writer knows, nothing like a complete skull of the species 

 has been discovered, or at least made known. 



A fine specimen showing the rear of the skull and the horn-cores 

 complete, except a very little at the extreme tip, is in the United States 

 National Museum and has the catalogue number 5726. Mr. Gilmore 

 in his paper previously referred to, on plate 10, published a figure 

 showmg a rear view of the skull. This figure is here reproduced, and 

 another is furnished which gives a view from above (pi. 14, figs. 1,2); 

 that is with the face dii'ected toward the observer. 



The following measurements have been taken, as shown in the 

 first column. Measurements of other skulls are presented in the 

 second, thu'd, and fourth columns. In the fifth column are measure- 

 ments of a skull of a bison found in the basin of the Jana River, 

 in Siberia, and described further on page 181. 



Measurements »f skulls. 



In No. 5726 the distance from the front of the foramen magnum 

 to the suture between the frontal and the nasals, the basinasal dis- 

 tance, is 266 mm. It has not been obtained in the other specimens . 



A view of the illustrations given here shows that this species had 

 horns considerably longer than those of any^of the species already 

 described in this paper. The horn-cores are directed, at the base 

 outward, sUghtly backward and downward, then they rise only 

 shghtly. Beyond the bases they sag so much that the lower borders 

 are on a level with the foramen magnum; and they rise at the tips 



