62 



Oxen 



ranging from the date of the Norfolk forest-bed to the Ilford brick-earth. 

 A series of skulls in the British iVluseum shows considerable variation in 

 individual size, and also in the curvature of the horn-cores, but none of the 

 specimens display differences apparently worthy ot specific distinction.' 

 Among these specimens are a skull and a detached horn-core obtained by 

 Captain Beechey from Kschscholtz Bay, Alaska, which were figured by 

 Dean Buckland, and subsequently made the types of B. crdssicornis by Sir 

 ]. Richardson. One of these has been identified by American writers with 





Fk;. 13.— Frontlet and horn-cores ot the Plistocenc Bison. From a specimen in the I'.ritish Museum 

 discovered in the Plistocenc brick-earth of Essex. 



Leidy's B. antiquiis^ while the second has been referred to yet another 

 species under the name of B. alaskois'is. The British Museum has other 

 specimens trom the Plistocenc deposits ot the Porcupine ri\er, Canada ; 

 and, taking Huropean and American specimens together, the whole series, 

 in my own opinion, should unquestionably be referred to a single species. 

 Moreover, so far as I can see, the American specimens present no closer 

 approximation tt) the living New World bison than do those from Iturope 

 to its relative of the Old World. It may also be pointed out that during 

 the Plistocenc period Asia and North America were almost certainly 



1 The two skulls of the European species represented in Fig. 14 show a considerable sexual 

 difference in the width ot the forehead and the size and curvature of the horns. 



