EXTINCT BI80N8 OF NORTH AMERICA— HAT. 



191 



the Vilni River, a tributary of the Lena, and which is now in the 

 Berlin Geological Institute. It has been studied by both La Baume 

 and HUzheimer, and from theii' papers have been obtained the meas- 

 urements here employed. A glance at Hilzheimer's illustrations 

 suggests at once the close resemblance of the skull to the one from 

 Hunter Creek, Alaska, here described. It is evident, however, that 

 the face, in front of the orbits, was much narrower than in the Alaska 

 skull; but this is the same difference which has been mentioned on 

 page 173, in the discussion of B. occidentalis. The Siberian skull may, 

 therefore, have belonged to a bull, the Alaskan to a cow. The fol- 

 lowing measurements of the two specimens are presented for com- 

 parison, and with them are given the same measurements compared 

 with the basinasal length taken as 100. 



Measurements, actual and reduced. 



Dimensions taken. 



Vilni River skull. 



Hunter Creek 

 skuU. 



Ditlerences between re- 

 duced measurements. 



Vilni 

 River 



Hunter 

 Creek. 



Bison eu- 

 ropxus. 



Bos Tpri- 

 migen- 



Basinasal length 



Distance from occipital crest to nasals 

 Width between bases of horn-cores... 



Width at rear of orbits 



Width at ear-openings 



Circumference of base of horn-cores. . 

 Length of horn along lower curve 



131 



12S.7 

 105.3 



mm. 

 100 



95.6 

 103.3 

 HI 



94 



Per cL 

 0.0 

 3.4 

 27.7 

 17.7 

 11.3 



Per cent. 

 0.0 

 5.6 

 14.0 

 12.2 

 8.3 



Per ct. 

 0.0 

 16.8 

 21.6 

 16.8 

 21.0 



A comparison of the reduced measurements, found in the second 

 and fourth columns, shows that the Siberian skull is considerably 

 broader than the Alaskan, especially between the bases of the horn- 

 cores; but likewise at the ear-openings and at the rear of the orbits. 

 In order that the meanmg of these differences may be, at least 

 partly explained, the figures in the last three columns are presented. 

 In the first of these three columns is given the difference between each 

 reduced measurement in the Siberian skull and the corresponding 

 one of the Alaskan. 



The figures in the next two columns are derived from Tables 3 and 5 

 of La Baume's paper. In his Table 3 are presented the reduced 

 measurements of 8 skulls of Bison europseus Owen (B. honasus) ; in his 

 Table 5 the reduced measurements of 17 skulls of Bos primigenius. 

 The figures in the next to the last column of the table shown above have 

 been obtained by taking the difference between the greatest and the 

 least of the measurements of each kind in Bison europseus; those of 

 the last column similarly from the reduced measurements of Bos 

 primigenius. It wall be seen that as regards the distance between the 



