770 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxi. 



variation has been carefully considered in the light of extensive series 

 of crania of Bison hison, and while the material on which the i)aper is 

 based is confessedly scanty, yet the species herein enumerated are 

 believed to be valid. 



EXPLANATION OF PLATES. 



Note. — The smaller divisons on the scale shown in some of the plates are centi- 

 meters, the larger are decimeters. 



Plate LXV. 

 Bison occidentalis Lucas. 

 Posterior view of the type, No. 4157, U.S.N.M., from Fort Yukon, Alaska. 



Plate LXVI. 



Bison occidentalis Lucas. 



Superior view of cranium from Gove County, Kansas, in the museum of the Uni- 

 versity of Kansas. 



Plate LXVII. 



Bison antiquus Leidy. 



Superior view of the type, a right-horn core, in the collection of the Academy of 

 Natural Sciences, Philadeljihia. 



Plate LXVIII. 



Bison antiquus Leidy. 



Posterior view of the type, a right-horn core, in the collection of the Academy of 

 Natural Sciences, Philadelphia. 



Plate LXIX. 



Bison antiquus Leidy. 



Posterior vie.v of a cranium from California, in the Academy of Natural Sciences, 

 Philadelphia. Described by Rhoads as Bison calif amicus. 



Plate LXX. 



Bison antiquus Leidy. 



Superior view of the specimen shown on Plate LXIX. 



Plate LXXI. 



Bison species. 



Posterior view of a specimen of bison from Ilford, Sussex, England. Recorded in 

 the catalogue of the British Museum as Bison honasus, No. 45392. 



Plate LXXII. 

 Bison. 

 Superior view of specimen shown on Plate LXXI. 



Plate LXXIII. 

 Bison crassicornis Richardson. 

 Superior view of a specimen from Alaska; No. 1584, U.S.N. M. 



Plate LXXIV. 

 Bison crassicornis Richardson. 

 Posterior view of specimen shown on Plate LXXIII. 



