﻿6 PLEISTOCENE MAMMALIA. 



hemisphere except the polar bear, the American black bear, and the blue bear of 

 Thibet) as one species. A. E. Brown 1 (1894) went farther than this, including even 

 the American black bear as a subspecies of U. arctos. In this view he was in 

 accordance with that previously reached by Allen, 3 who, however, afterwards changed 

 his opinion 3 with regard to this point. In the paper just referred to 3 he gave a 

 valuable table of measurements showing the great individual variability in bears' 

 skulls from the same locality, and considered that, though U. americanus might be 

 distinct, there was a complete passage between the brown and grizzly bears. 



The remarkable individual variability was still more impressively shown by 

 E. Schaff 1 ' (1889) in a paper on a collection of thirty-five skulls all obtained from a 

 limited area in Russia. The variability of the European bears was shown to be 

 more than paralleled by those of America in C. H. Merriam's paper, 5 which was based 

 on a study of more than two hundred skulls, a series of as many as ninety-five 

 having been obtained from one locality. The conclusions which he drew were, 

 however, widely different from those drawn by Brown and Allen ; for he not only 

 considered that the American "brown" bears (of which he made a number of new 

 species) were specifically distinct from the European, but separated the black bear 

 subgenerically. 



The difficulty of distinguishing between the different species of fossil bears is 

 further illustrated by the important papers by Gautlry and Boule, G and E. T. 

 Newton. 7 The former authors showed that even the loss of the three anterior 

 upper premolars is not absolutely characteristic of the cave bear, as individuals 

 of the smaller race from Gargas retain pm, 3. The close connection between the 

 bears of the brown and grizzly types is illustrated by the fact that they considered 

 U. prisons to come nearer to U. arctos, especially as regards the humerus, than to 

 U. horribilis, with which it is usually thought to be identical. 



Newton, in describing the Vertebrata from the Forest Bed, agreed with Owen 

 in assigning the jaw figured in the ' British Fossil Mammals,' p. 100, to IT. spel&us, 

 in spite of its small size, while he assigned another specimen to U. spelseus in spite 

 of its retaining pm. 1. 



i ' Proc. Acad. Nat. Sci. Pliilad.,' xlvi, 1894, p. 119. 



2 ' Bull. Mus. Comp. Zool.,' i, 1869, p. 184. 



3 ' Bull. U. S. Geol. Surv. of Territories,' ii, uo. 4, 1876, p. 334. 



4 ' Archiv f iir Naturgeschichte,' 1889, p. 244. 



s ' Proc. Biol. Soc. Washington,' x, 1896, pp. 65-83. 



' Mat. pour l'histoire des temps quaternaires,' fasc. iv, p. 105 (1892). 



7 " Vertebrata of Forest Bed Series," ' Mem. Geol. Surv.,' p. 5 (1882). 



