28 PLEISTOCENE MAMMALIA. 



was met with showing the peculiar uniform tuberculatum of some of the cave bear 

 specimens, some of the small mandibles attributed to this species have the surface 

 of m. 3 wholly or partially ridged as in bears of the arctos type. 



(5) Boyd Dawkins 1 states that the canine is on the whole more massive in the 

 cave bear than in the grizzly, especially as regards the root. "It is also generally 

 but not always absolutely larger in the crown, as Prof. Busk has remarked in his 

 description of the teeth from the Brixham Cave." 



((>) Distinguishing Characters drawn from Parts other than the Teeth. 



(1) The relatively enormous size of the core bear. — The size of the cave bear's 

 skull, though as a rule much greater than that of the fossil representatives of the 

 brown and grizzly bears, is not so much greater than that of the huge grizzlies of 

 Alaska and brown bears of Kamtchatka. Also, as pointed out by Owen, a mandible 

 from the Forest Bed which he figures, 2 and which on account of the complete 

 absence of the anterior premolars he attributes to U. spelains, is a good deal 

 smaller than a second mandible from Manea fen, which, owing to the large alveoli 

 for pm. 1, 3, he regards as belonging to U. arctos. 



(2) The relatively great length of the interspace between c. and pm. 4 in the cave 

 bear. — This certainly is subject to a very large amount of variation, as the table of 

 measurements on p. 11 shows (cf. also PI. V). Busk says it is a feature distin- 

 guishing the cave from the brown bear but not from the grizzly. Owen quotes it 

 as also distinguishing the cave bear from the grizzly. 



(3) The relative narrowness of the posterior narial opening in the care bear. — 

 This, again, is a feature showing much variability (see the measurements on p. 11). 



(4) The arched character of the frontal region in the cave bear's skull. — In many 

 of the huge skulls from French, German, and Belgian caves this is very marked, 

 the skull rising into two considerable bosses at the junction of the frontals and 

 nasals owing to the enlargement of the frontal sinuses. In some of the smaller 

 cave bear skulls, on the other hand, it is scarcely more noticeable than in those of 

 the brown and grizzly bears. It is probably a character which increased with age 

 and became specially marked in the old males. Owen refers to de Blainville's 

 suggestion, that the development of the frontal sinuses depended on the cave bear's 

 breathing a fresher, dryer, and more invigorating atmosphere than its present-day 

 allies. 



(5) The rapid approach of the temporal crests so as to form an obtuse angle 

 posteriorly. 



1 ' Quart. Journ. Geol. Soc.,' xxxi, 1875, p. 251. 



2 'Brit. Fosa. Maiuiu. ami Birds,' p. 1(J(J. 



