336 



than in the others. Specimens of U. horribilis, from the same locality, 

 however, differ more among themselves in this respect than the average 

 difference between U. horribilis and U. arctos. The teeth, however, 

 in U. arctos are relatively larger than in U. horribilis^ the difference be- 

 ing quite appreciable. The teeth of the Franklin Bay specimens ( U. 

 richardsoni)) on the other hand, are of the same relative size as in the 

 Old World examples of U. arctos. 



After a careful consideration of the subject, I believe the Barren 

 Ground Bear of Eichardson ( U. richardsoni of Mayne Reid) to be not 

 even subspecifically distinct from the true U. arctos of the Old World. 

 The Grizzly, from its larger size, widely different geographical distribu- 

 tion, apparently larger claws, slight differences in the dentition and in 

 the'form of the frontal region of the skull, may be so regarded ( U. arctos 

 subsp. horribilis), as it can hardly be doubted that it gradually passes 

 into the Barren Ground form. 



The subjoined table of detailed measurements of the skulls of U. arctos 

 horribilis indicates the wide range of individual variation that may be 

 looked for among skulls from the same locality. These variations not 

 only affect the ratio of width to length, through the greater or less 

 elongation of the facial portions of the skull as compared to the rest, 

 but also all the other proportions are more or less variable, including 

 even the teeth themselves. Thus, two specimens from California, of 

 practically the same length (15.60 and 15.40), vary in breadth from 8.10 

 to 9.05, while two others vary still more, one, with a breadth of 9.20, 

 having a length of only 14.50, while another, with a breadth of 8.50, has 

 a length of 16.00 ! In these last, the ratio of width to length varies from 

 0.53 to 0.63. In two California specimens of practically the same length 

 (15.60 and 15.75), the length of the last molar varies from 1.43 to 1.58. 

 In the series of California specimens alone, the length of the last molar 

 varies from 1.35 to 1.66, and the width of the same from 0.67 to 0.80, the 

 widest tooth being, furthermore, not the longest. As already stated, the 

 last upper molar attains its greatest width near the anterior border, but 

 in several specimens the width of the anterior third is nowhere greater 

 than the width of the tooth at its middle $ and the same is also some- 

 times true in U. richardsoni. 



