BIOLOGICAL PAPERS. 159 



museum of the University of Kansas. An exceptionally fine pair of 

 horns of B. laiifrons was unearthed in Sheridan county. This speci- 

 men measures some eight feet from tip to tip of the horn cores. 



A brief description of the new species will be sufficient. As will 

 be seen from figure 10, the horn core descends rapidly from the level 

 of the forehead and barely attains it again at the upcurved tip. Viewed 

 from above, the core is observed to rake strongly and persistently back- 

 ward, so that it has passed the level of the occipital region a short 

 distance out from the line indicating the limit of the horn attach- 

 ment. In section the core is subcircular in outline, and the circum- 

 ference at the base exceeds the estimated length along the upper 

 curve. The specimen thus falls within the group containing B. hison 

 and B. occidentalis. It may be distinguished from B. hison by the 

 greater size of the horns and by their rapid backward extension be- 

 yond the line of the occipital crest. It is separated from B. occiden- 

 talis by the strong downward sweep of the horns. A comparison of 

 the measurements of the horn cores from specimens of the three 

 species of this group is shown in the following table : 



B. bison. B. Occident. B. kansensis. 

 mm, mm. mm. 



Vertical diameter 76 108 90 



Transverse diameter 81 108 97 



Circumference at base 253 343 290 



Length along upper curve 180 318 250 (est.) 



Length along lower curve 235 372 265 (est.) 



Distance between tips 650 875 840 (est.) 



These measurements are taken from specimens in the museum of 

 the University of Kansas. 



